A core / shell type nano-silver-based composite material, a preparation method thereof and an antibacterial application thereof

Abstract

The application discloses a kind of core / shell type nano silver-based composite material and its preparation method and antibacterial application, the core / shell type nano silver-based composite material is with spherical nanometer cerium dioxide (n-CeO2) as substrate, nano silver is loaded on the surface of the spherical nanometer cerium dioxide by photo-deposition method and obtained nano silver@cerium dioxide composite material with silver-loaded surface, wherein the spherical nanometer cerium dioxide is prepared by alcohol hot method.The application avoids the problems of poor antibacterial property of nano cerium dioxide particles alone, easy aggregation of nano silver alone leading to sharp reduction of antibacterial performance and insufficient excellent oxidation resistance compared with prior art, and the core / shell type nano silver-based composite material has high efficient antibacterial property, physical and chemical stability, excellent photocatalytic property and redox property for escherichia coli and staphylococcus aureus.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antibacterial materials, in particular to a core / shell type nano-silver-based composite material and its preparation method and antibacterial application. BACKGROUND

[0002] Nano-silver Ag is one of the relatively mature antibacterial materials at present, and there are many research results. It has been applied in clinical practice and has the characteristics of broad-spectrum, high efficiency and not easy to make pathogenic bacteria resistant. Studies have shown that a variety of anisotropic silver nanocrystals have antibacterial activity against a variety of bacteria. This shape effect means that silver nanocrystals of different shapes have different antibacterial activities due to different crystallographic orientations. The bactericidal mechanism of Ag is that Ag ions enter the cell and combine with the DNA molecule, replacing the hydrogen bond in the double helix structure, and ultimately causing the DNA molecule structure to deform and damage, thereby inhibiting DNA replication, RNA formation and protein synthesis, and making the bacteria inactivate. The antibacterial mechanism of nano-silver is physical antibacterial and does not cause bacteria to develop resistance. However, due to the characteristics of easy aggregation and oxidation, nano-silver cannot be used alone in drugs or wound dressings, and needs to be loaded on other materials to form a composite material to stabilize the nano-particles.

[0003] In recent years, with the development of nanotechnology, nano-particles that can effectively remove ROS by simulating the activity of enzymes in the body have been developed. Due to the redox regulation characteristics of cerium oxide nanoparticles, cerium has found a wide range of applications in biomedical applications. For example, a study has shown that a cerium-modified polymer nanofiber patch can not only remove ROS, but also inhibit myocardial hypertrophy. Cerium dioxide is often used in the field of biological medicine due to its good biocompatibility, low cytotoxicity, no hemolysis, and the ability to promote wound repair. It also has fast redox ability and strong metal carrier interaction. However, nano-cerium dioxide particles alone have poor antibacterial properties.

[0004] Therefore, how to effectively combine nano-silver with excellent antibacterial properties and cerium oxide nanoparticles with excellent biological properties and achieve synergistic effect to obtain antibacterial materials with excellent antibacterial properties and biocompatibility has become a research hotspot and difficulty. SUMMARY

[0005] The present application relates to the technical field of antibacterial materials, in particular to a core / shell type nano-silver-based composite material and its preparation method and antibacterial application.

[0006] The technical scheme adopted by the present application to achieve the above-mentioned purpose is:

[0007] The core-shell type nano-silver-based composite material (Ag@n-CeO2) is prepared by loading nano-silver on the surface of spherical nano-cerium dioxide (n-CeO2) through a photo-deposition method, and the nano-silver@cerium dioxide composite material with silver loaded on the surface is obtained, namely the core-shell type nano-silver-based composite material.

[0008] Further, the spherical nano-cerium dioxide (n-CeO2) is prepared by an alcohol heating method.

[0009] The application further discloses a preparation method of the aforementioned core-shell type nano-silver-based composite material, which comprises the following steps.

[0010] S1, synthesizing nano-cerium dioxide (n-CeO2):

[0011] 1) adding cerium nitrate, deionized water, citric acid and polyvinylpyrrolidone into ethylene glycol to obtain solution A; then, the solution A is placed in a reaction kettle to react at high temperature for a certain time, and then cooled to room temperature, and the precipitate B is obtained through separation;

[0012] 2) the precipitate B is centrifuged, washed and dried to obtain precipitate C, and then the precipitate C is placed in a tube furnace to react for a certain time to obtain nano-cerium dioxide powder;

[0013] S2, preparing the core-shell type nano-silver-based composite material (Ag@n-CeO2):

[0014] 3) dispersing the obtained nano-cerium dioxide powder in pure water to prepare a suspension D, and then mixing the suspension D with silver nitrate and methanol, and reacting for a certain time under irradiation of a high-pressure mercury lamp to obtain a suspension E;

[0015] 4) the suspension E is placed in a centrifuge tube, washed and dried in a freeze dryer to obtain the nano-silver@cerium dioxide composite material with silver loaded on the surface, namely the core-shell type nano-silver-based composite material.

[0016] Further, the mass-volume relationship of the components added in the step 1) is as follows: 0.8-2.0 g of cerium nitrate, 1.5-3.0 mL of citric acid, 0.4-0.7 g of polyvinylpyrrolidone, 1.5-3.0 mL of deionized water and 50.0-55.0 mL of ethylene glycol.

[0017] Further, the high-temperature reaction condition of the solution A in the step 1) is that the solution A is reacted at 120-200 DEG C for 120-240 min.

[0018] Further, the washing of the precipitate B in step 2) is distilled water washing 3 times and ethanol washing 1 time; the drying temperature of the precipitate B in step 2) is 50-70 DEG C; the reaction condition of the precipitate C in step 2) is heat treatment at 380-450 DEG C for 180-300 min.

[0019] Further, the mass concentration of the suspension D in step 3) is 8-20 mg / mL, the pure water is 5 mL, and the mass of the nano cerium dioxide powder in the suspension D is 40-100 mg.

[0020] Further, the mass-volume ratio of the components added in step 3) is: silver nitrate 5-15 mg, methanol 0.5-1.5 mL.

[0021] Further, the irradiation time of the high-pressure mercury lamp in step 3) is 25-40 min.

[0022] The application further discloses an antibacterial application of the core / shell type nano silver-based composite material, the core / shell type nano silver-based composite material has good bacteriostasis and sterilization on escherichia coli and staphylococcus aureus, and has good antibacterial properties in the fields of textiles, plastics, rubber, ceramics, medical treatment and biological materials.

[0023] The cerium oxide nanoparticles have redox regulation activity, are effective ROS scavengers, and have unique conversion capacity between two oxidation states Ce2O3 and CeO2; in the oxygen exchange process, the loss of lattice oxygen atoms in the cubic fluorite lattice generates oxygen vacancies in the cerium oxide, the vacancies can be filled by atomic oxygen to generate new vacancies, cause the migration rate of lattice oxygen, and quickly refill the surface oxygen vacancies; since the CeO2 nanoparticles can simulate the activity of SOD and CAT enzymes through the redox regulation behavior, the CeO2 nanoparticles are called 'nanoparticles'. The nano silver is loaded on the surface of the cerium dioxide by the photodeposition method based on the cerium oxide nanoparticles, and the synergistic effect is obtained, so that the antibacterial material with excellent antibacterial property and biocompatibility is obtained.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] (1) The application is synthesized in two steps, the nano cerium dioxide particles are prepared by using an alcohol heating method, the spherical nano cerium dioxide (n-CeO2) is used as a base, and the nano silver is loaded on the surface of the cerium dioxide by the photodeposition method, so that the nano silver is attached more uniformly and more closely, and thus the core / shell type nano silver-based composite material, i.e., the nano silver@cerium dioxide composite material with silver on the surface, is formed, which is different from the existing silver-doped cerium dioxide method, avoids the problems of poor antibacterial property of the nano cerium dioxide particles alone, easy aggregation of the nano silver alone, sharp reduction of the antibacterial performance and insufficient excellent antioxidant property, and has excellent bacteriostatic performance and antioxidant performance.

[0026] (2) The core / shell type nano-silver-based composite material of the present application is simple to prepare, and when used as an antibacterial agent, based on its strong metal carrier interaction effect, it can become a high-efficiency antibacterial material when the amount of nano-silver loaded is less than 6% (wt%), and can be widely applied in various antibacterial fields, such as textiles, plastics, rubber, ceramics, medical treatment, biological materials, etc., and has excellent performance.

[0027] (3) The core / shell type nano-silver-based composite material of the present application has the advantages of low bacteriostatic and bactericidal concentration, high efficiency, low cost, etc., and is stable and not easy to fail, and also has the advantages of excellent photocatalytic property, excellent oxidation-reduction performance, good antibacterial property, good physical and chemical stability, good dispersibility, diversity of surface properties, small harm to the environment, etc.

[0028] The above is a summary of the technical scheme of the present application, and the present application will be further described in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 SEM image of the core / shell type nano-silver-based composite material of the present embodiment;

[0030] Figure 2 EDX image corresponding to the core / shell type nano-silver-based composite material of the present embodiment;

[0031] Figure 3 TEM image of the core / shell type nano-silver-based composite material of the present embodiment;

[0032] Figure 4 XRD image of the core / shell type nano-silver-based composite material of the present embodiment;

[0033] Figure 5 Schematic diagram of the relationship between the antibacterial rates of the core / shell type nano-silver-based composite material of the present embodiment on E. coli and S. aureus at different concentrations;

[0034] Figure 6 Another schematic diagram of the relationship between the antibacterial rates of the core / shell type nano-silver-based composite material of the present embodiment on E. coli and S. aureus at different concentrations;

[0035] Figure 7 Schematic diagram of the relationship between the scavenging rates of the core / shell type nano-silver-based composite material of the present embodiment on DPPH· free radicals at different concentrations. DETAILED DESCRIPTION

[0036] In order to make the objects, technical schemes and advantages of the present application clearer, specific embodiments are described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0037] The preparation process of the core / shell type nano silver-based composite material of the present application includes two steps:

[0038] The first step is the synthesis route of nano cerium dioxide: taking cerium nitrate (0.8-2.0 g), citric acid (1.5-3.0 mL), polyvinylpyrrolidone (0.4-0.7 g), deionized water (1.5-3.0 mL), and ethylene glycol (50.0-55.0 mL) as the basic formula raw material components, alcohol heat reaction at 120-200℃ for 120-240 min, the obtained crude product is treated by purification, and then the obtained precipitate C is placed in a tube furnace for reaction for a certain time to obtain nano cerium dioxide powder for standby.

[0039] The second step is the synthesis route of nano silver@cerium dioxide composite material: taking the suspension liquid D of nano cerium dioxide and pure water (8-20 mg / mL, 5 mL), silver nitrate (5-15 mg), and methanol (0.5-1.5 mL) as the basic formula raw material components, irradiation under high-pressure mercury lamp for 25-40 min, the obtained crude product is treated by purification and freeze-drying for standby.

[0040] Specifically, the present application is also described in detail by the following embodiments:

[0041] Example 1: The core / shell type nano silver-based composite material and its preparation method and antibacterial application provided by the present embodiment, the core / shell type nano silver-based composite material is a nano silver@cerium dioxide composite material with silver loaded on the surface, which is obtained by loading nano silver on the surface of spherical nano cerium dioxide (n-CeO2) through photo-deposition method, and the spherical nano cerium dioxide (n-CeO2) is prepared by alcohol heat method. The specific preparation method includes:

[0042] 1) 2.0 g of cerium nitrate, 2 mL of deionized water, 2 mL of citric acid, 0.5 g of polyvinylpyrrolidone, and 52 mL of ethylene glycol are added, stirred for 30 min to obtain solution A;

[0043] 2) Transfer solution A into a polytetrafluoroethylene liner, then put it into a stainless steel reaction kettle for high-temperature reaction at 180℃ for 200 min, cool the solution to room temperature, and pour off the upper yellow-brown clear liquid to obtain purple precipitate B;

[0044] 3) Transfer the precipitate B to a centrifuge bottle, wash it with distilled water for 3 times and with ethanol for 1 time, then put it into a 70℃ oven for drying, and obtain precipitate C after complete drying.

[0045] 4) The precipitate C was transferred to a crucible and then put into a tube furnace to react at 400°C for 240 min, obtaining a light yellow cerium dioxide powder, which was stored for later use.

[0046] 5) The powder-like nano cerium dioxide (n-CeO2) was dispersed in ultrapure water to prepare a suspension D (nano cerium dioxide 8 mg / mL, 5 mL). The suspension D 40 mg, 10 mg silver nitrate and 0.5 mL methanol were mixed to obtain a suspension E under the irradiation of a high-pressure mercury lamp for 40 min.

[0047] 6) The suspension E was transferred to a centrifuge tube, washed with ultrapure water and anhydrous ethanol for several times, and then dried in a freeze dryer to obtain a powder-like core / shell type nano silver-based composite material Ag@n-CeO2.

[0048] The powder-like core / shell type nano silver-based composite material, i.e. nano silver@cerium dioxide composite material (Ag@n-CeO2) prepared in this example, is a yellow-brown powder insoluble in water and has no odor. Because the surface-loaded nano silver can destroy bacterial cell membranes, mitochondria, DNA and the like, and can interact with cerium dioxide to produce reactive oxygen species ROS, this property can be used to achieve high-efficiency sterilization.

[0049] Example 2: The core / shell type nano silver-based composite material and its preparation method and antibacterial application provided in this example are basically the same as those in Example 1, except that:

[0050] 1) 1.517 g of cerium nitrate, 1.5 mL of deionized water, 3.0 mL of citric acid and 0.7 g of polyvinylpyrrolidone were added to 55 mL of ethylene glycol, and stirred for 30 min to obtain a solution A;

[0051] 2) The solution A was transferred to a polytetrafluoroethylene liner and then loaded into a stainless steel reaction kettle to react at 120°C for 240 min. After the solution was cooled to room temperature, the upper yellow-brown clear liquid was poured off to obtain a purple precipitate B;

[0052] 3) The precipitate B was transferred to a centrifuge bottle, washed with distilled water for 3 times and ethanol for 1 time, and then dried in a 50°C oven. After complete drying, a precipitate C was obtained.

[0053] 4) The precipitate C was transferred to a crucible and then put into a tube furnace to react at 400°C for 180 min, obtaining a light yellow cerium dioxide powder, which was stored for later use.

[0054] 5) The powdered nanometer cerium dioxide (n-CeO2) is dispersed in ultrapure water to prepare a suspension D (nanometer cerium dioxide 20 mg / mL, 5 mL), and the suspension D 100 mg, 15 mg silver nitrate, 1.5 mL methanol are mixed to obtain the suspension E under the irradiation of a high-pressure mercury lamp for 40 min.

[0055] Example 3: The core / shell type nanometer silver-based composite material and its preparation method and antibacterial application provided in this example are basically the same as those in Example 1, except that:

[0056] 1) 1.5 g of cerium nitrate, 2 mL of deionized water, 2 mL of citric acid, and 0.4 g of polyvinylpyrrolidone are added to 50 mL of ethylene glycol, and stirred for 30 min to obtain a solution A;

[0057] 2) The solution A is transferred to a polytetrafluoroethylene liner, and then loaded into a stainless steel reaction kettle for high-temperature reaction at 140°C for 200 min. After the solution is cooled to room temperature, the upper yellow-brown clear liquid is poured off to obtain a purple precipitate B;

[0058] 3) The precipitate B is transferred to a centrifuge bottle, washed with distilled water for 3 times and ethanol for 1 time, and then placed in a 60°C oven for drying. After complete drying, a precipitate C is obtained.

[0059] 4) The precipitate C is transferred to a crucible, and then placed in a tube furnace for reaction at 380°C for 300 min to obtain a light yellow cerium dioxide powder, which is stored for use.

[0060] 5) The powdered nanometer cerium dioxide (n-CeO2) is dispersed in ultrapure water to prepare a suspension D (nanometer cerium dioxide 20 mg / mL, 5 mL), and the suspension D 100 mg, 15 mg silver nitrate, 1.5 mL methanol are mixed to obtain the suspension E under the irradiation of a high-pressure mercury lamp for 40 min.

[0061] Example 4: The core / shell type nanometer silver-based composite material and its preparation method and antibacterial application provided in this example are basically the same as those in Example 1, except that:

[0062] 1) 0.8 g of cerium nitrate, 2.5 mL of deionized water, 3.0 mL of citric acid, and 0.6 g of polyvinylpyrrolidone are added to 50 mL of ethylene glycol, and stirred for 30 min to obtain a solution A;

[0063] 2) The solution A is transferred to a polytetrafluoroethylene liner, and then loaded into a stainless steel reaction kettle for high-temperature reaction at 180°C for 120 min. After the solution is cooled to room temperature, the upper yellow-brown clear liquid is poured off to obtain a purple precipitate B;

[0064] 3) Transfer the precipitate B to a centrifuge bottle, wash with distilled water for 3 times, ethanol for 1 time, and then put it into a 60°C oven for drying. After completely dried, precipitate C is obtained.

[0065] 4) Transfer the precipitate C to a crucible, and then put it into a tube furnace for reaction at 390°C for 200 min. A light yellow cerium dioxide powder is obtained and stored for later use.

[0066] 5) Disperse the powder-like nano cerium dioxide (n-Ce02) in ultrapure water to prepare a suspension D (nano cerium dioxide 12 mg / mL, 5 mL). Mix 60 mg of the suspension D, 5 mg of silver nitrate, and 1.0 mL of methanol to obtain a suspension E under irradiation of a high-pressure mercury lamp for 30 min.

[0067] Example 5: The core / shell type nano silver-based composite material and its preparation and antibacterial application provided in the example are basically the same as those in Example 1, except that:

[0068] 1) Add 1.7 g of cerium nitrate, 3.0 mL of deionized water, 1.5 mL of citric acid, and 0.4 g of polyvinylpyrrolidone to 53 mL of ethylene glycol, and stir for 30 min to obtain a solution A;

[0069] 2) Transfer the solution A to a polytetrafluoroethylene liner, and then put it into a stainless steel reaction kettle for high-temperature reaction at 190°C for 120 min. After the solution is cooled to room temperature, the upper layer of yellow-brown clear liquid is poured off to obtain a purple precipitate B;

[0070] 3) Transfer the precipitate B to a centrifuge bottle, wash with distilled water for 3 times, ethanol for 1 time, and then put it into a 50°C oven for drying. After completely dried, precipitate C is obtained.

[0071] 4) Transfer the precipitate C to a crucible, and then put it into a tube furnace for reaction at 380°C for 300 min. A light yellow cerium dioxide powder is obtained and stored for later use.

[0072] 5) Disperse the powder-like nano cerium dioxide (n-Ce02) in ultrapure water to prepare a suspension D (nano cerium dioxide 8 mg / mL, 5 mL). Mix 40 mg of the suspension D, 12 mg of silver nitrate, and 0.5 mL of methanol to obtain a suspension E under irradiation of a high-pressure mercury lamp for 25 min.

[0073] Example 6: The core / shell type nano silver-based composite material and its preparation and antibacterial application provided in the example are basically the same as those in Example 1, except that:

[0074] 1) Add 1.517 g of cerium nitrate, 2.2 mL of deionized water, 2.5 mL of citric acid, and 0.5 g of polyvinylpyrrolidone to 53 mL of ethylene glycol, and stir for 30 min to obtain a solution A;

[0075] 2) Transfer solution A into a polytetrafluoroethylene liner, and then load into a stainless steel reaction kettle for high-temperature reaction at 200 DEG C for 150 min; after the solution is cooled to room temperature, pour off the upper yellow-brown clear liquid to obtain purple precipitate B;

[0076] 3) Transfer precipitate B into a centrifuge bottle, wash with distilled water for 3 times, wash with ethanol for 1 time, and then place into a 50 DEG C oven for drying; after complete drying, obtain precipitate C.

[0077] 4) Transfer precipitate C into a crucible, and then place into a tube furnace for reaction at 420 DEG C for 200 min to obtain light yellow cerium dioxide powder, which is stored for use.

[0078] 5) Disperse the powdered nano cerium dioxide (n-CeO2) in ultrapure water to configure a suspension D (nano cerium dioxide 10 mg / mL, 5 mL); mix 50 mg of the suspension D, 10 mg of silver nitrate and 1.0 mL of methanol to obtain a suspension E under irradiation of a high-pressure mercury lamp for 35 min.

[0079] The implementation process of the present application also applies the following mode to the related product core / shell type nano silver-based composite material in the above embodiment for application test, as shown in the following table: Figures 1-4 The SEM and EDX graphs are obtained by scanning electron microscope test, and the TEM graph is obtained by transmission electron microscope test, which shows that the core / shell type nano silver-based composite material, i.e., nano silver@cerium dioxide composite material (Ag@n-CeO2), is obtained by the method, and the XRD graph is obtained by corresponding test. The table corresponding to the test results of the EDX graph is as follows:

[0080]

[0081] The present application also performs antibacterial test on the core / shell type nano silver-based composite material, i.e., nano silver@cerium dioxide composite material Ag@n-CeO2, using Escherichia coli and Staphylococcus aureus, and tests the minimum inhibitory concentration and antibacterial rate thereof. The specific steps include the following steps:

[0082] 1) Disperse any powdered core / shell type nano silver-based composite material, i.e., nano silver@cerium dioxide composite material Ag@n-CeO2, in ultrapure water to configure a suspension F of a certain concentration; use a 96-well cell culture plate to test the minimum inhibitory concentration of Ag@n-CeO2 of a certain mass concentration on Escherichia coli and Staphylococcus aureus, respectively, and mark as MIC. As shown in the following table: Figure 5

[0083] ​2) The obtained any powdery core / shell type nano-silver-based composite material, namely nano-silver@cerium dioxide composite material Ag@n-CeO2, is dispersed in ultrapure water, and a certain mass concentration of Ag@n-CeO2 is respectively tested for antibacterial rate against E. coli and Staphylococcus aureus using a flat plate coating method, and is recorded as MBC. As shown in Figure 5

[0084] The application also determines the antioxidation performance of the core / shell type nano-silver-based composite material Ag@n-CeO2, and obtains the relationship between DPPH free radical scavenging rate and sample concentration at each concentration, as shown in Figure 6

[0085] It can be seen that the core / shell type nano-silver-based composite material has the advantages of low bacteriostatic and bactericidal concentration, high efficiency, low cost, excellent redox performance, good antibacterial property, material stability, non-failure, photocatalytic property, physical and chemical stability, good dispersibility, surface property diversity, small environmental hazards and the like.

[0086] According to the disclosure and teaching of the above description, those skilled in the art of the present application can also make changes and modifications to the above embodiments. Therefore, the present application is not limited to the specific embodiments disclosed and described above, and some modifications and changes of the application should also fall within the protection scope of the claims of the present application.​​

Claims

1. A core / shell type nano silver-based composite material, characterized in that, The application discloses a core-shell type nano-silver-based composite material (Ag@n-CeO2) which is prepared by loading silver on the surface of spherical nano cerium dioxide (n-CeO2) through a photo-deposition method. The nano cerium dioxide is prepared by the following method: 1) adding cerium nitrate, deionized water, citric acid and polyvinylpyrrolidone into ethylene glycol to obtain solution A; then, the solution A is placed in a reaction kettle for high-temperature reaction for a certain period of time, and then cooled to room temperature, and then the precipitate B is obtained through separation; 2) the precipitate B is centrifuged, washed and dried to obtain the precipitate C, and then the precipitate C is placed in a tube furnace for reaction for a certain period of time to obtain nano cerium dioxide powder; the high-temperature reaction condition of the solution A in the step 1) is 120-200 DEG C for 120-240 min; the mass-volume relationship of the components added in the step 1) is as follows: 0.8-2.0 g of cerium nitrate, 1.5-3.0 mL of citric acid, 0.4-0.7 g of polyvinylpyrrolidone, 1.5-3.0 mL of deionized water and 50.0-55.0 mL of ethylene glycol; and the reaction condition of the precipitate C in the step 2) is heat treatment at 380-450 DEG C for 180-300 min.

2. The method of producing the core / shell nano silver-based composite material according to claim 1, characterized in that, The method comprises the following steps: S1, synthesizing nano cerium dioxide: 1) adding cerium nitrate, deionized water, citric acid and polyvinylpyrrolidone into ethylene glycol to obtain solution A; then, the solution A is placed in a reaction kettle for high-temperature reaction for a certain period of time, and then cooled to room temperature, and then the precipitate B is obtained through separation; 2) the precipitate B is centrifuged, washed and dried to obtain the precipitate C, and then the precipitate C is placed in a tube furnace for reaction for a certain period of time to obtain nano cerium dioxide powder; S2, preparing the core-shell type nano-silver-based composite material: 3) dispersing the obtained nano cerium dioxide (n-CeO2) powder in pure water to prepare a suspension D, and then mixing the suspension D with silver nitrate and methanol and reacting for a certain period of time under the irradiation of a high-pressure mercury lamp to obtain a suspension E; 4) placing the suspension E in a centrifuge tube, washing and drying in a freeze dryer to obtain the silver / cerium dioxide composite material with silver on the surface, namely the core-shell type nano-silver-based composite material; The mass-volume relationship of the components added in the step 1) is as follows: 0.8-2.0 g of cerium nitrate, 1.5-3.0 mL of citric acid, 0.4-0.7 g of polyvinylpyrrolidone, 1.5-3.0 mL of deionized water and 50.0-55.0 mL of ethylene glycol; The high-temperature reaction condition of the solution A in the step 1) is 120-200 DEG C for 120-240 min; The washing of the precipitate B in the step 2) is distilled water washing for 3 times and ethanol washing for 1 time; the drying temperature of the precipitate B in the step 2) is 50-70 DEG C; and the reaction condition of the precipitate C in the step 2) is heat treatment at 380-450 DEG C for 180-300 min.

3. The process for preparing core / shell nano silver-based composite material according to claim 2, characterized in that, The mass concentration of the suspension D in the step 3) is 8-20 mg / mL, the pure water is 5 mL, and the mass of the nano cerium dioxide powder in the suspension D is 40-100 mg.

4. The process for preparing core / shell nano silver-based composite material according to claim 2, characterized in that, The mass-volume ratio of the components added in the step 3) is: silver nitrate 5-15 mg, methanol 0.5-1.5 mL.

5. The process for preparing core / shell nano-silver-based composite material according to claim 2, characterized in that, The irradiation time of the high-pressure mercury lamp in the step 3) is 25-40 min.

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