A CoO@Ag nanozyme, its preparation method and application

Abstract

The present invention discloses a CoO@Ag nanozyme, its preparation method and application. The preparation method of the CoO@Ag nanozyme is as follows: Dissolve a cobalt salt and a stabilizer in water to obtain a cobalt salt solution. Add a reducing agent to the cobalt salt solution and stir to react, then add a silver nitrate solution and continue to stir. Finally, add a quenching agent to quench the reaction, and the obtained product is the CoO@Ag nanozyme. The preparation method of the CoO@Ag nanozyme provided by the present invention requires simple reaction equipment and mild reaction conditions. The prepared product has excellent antibacterial properties and is suitable for large-scale application and production. The present invention applies the CoO@Ag nanozyme to the preparation of a CAP fiber membrane. The obtained CAP fiber membrane has functions of high-efficiency antibacterial, real-time protection and reusability, has excellent antibacterial properties, and meets the application scenarios of personal protective materials in the presence or absence of light sources.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of functional materials, and particularly relates to a CoO@Ag nanozyme and a preparation method thereof, and an application of the CoO@Ag nanozyme in the preparation of a mask with high-efficiency antibacterial, real-time protection, and reusable functions. Background Art

[0002] Air pollution caused by particulate matter and pathogenic bacteria seriously endangers the ecological environment and human health. As one of the non-pharmaceutical intervention measures for respiratory infections, using masks is an important way to prevent infections and transmissions. However, masks cannot be reused or recycled after use, thus exacerbating the microplastic problem. In addition, commercial masks usually consist of a polypropylene (PP) melt-blown non-woven fabric core and lack self-cleaning performance. Long-term use of masks can lead to the accumulation and reproduction of bacteria and other microorganisms on their surfaces, which may damage personal health and cause secondary transmission. Nanomaterials with antibacterial properties (such as metal materials, carbon materials, and polymers) have been used in textiles to develop personal protective equipment that can effectively combat pathogenic bacteria. However, the preparation of some bactericides is complex and consumable. Moreover, the traditional method of impregnating nanomaterials into fabrics has great limitations, easily leading to the separation of nanomaterials and insufficient surface functionalization. In contrast, preparing nanofiber membranes loaded with nanomaterials by electrospinning methods has stronger dispersibility, stability, and load controllability, providing great potential for developing antibacterial protection devices. Therefore, it is urgent to design and prepare nanomaterials with simple preparation, low cost, and excellent inherent antibacterial properties, and to develop masks with high-efficiency antibacterial, real-time protection, and reusability by spinning methods, which is crucial for improving personal and public health. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a CoO@Ag nanozyme and a preparation method and application thereof. The present invention prepares a CoO@Ag nanozyme with excellent antibacterial performance through a simple process, and applies the CoO@Ag nanozyme to mask preparation. The obtained mask has excellent inherent antibacterial ability and achieves the effects of high performance and real-time protection.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] The first aspect of the present invention is to provide a preparation method of a CoO@Ag nanozyme, including the following steps:

[0006] Dissolve a cobalt salt and a stabilizer in water to obtain a cobalt salt solution, add a reducing agent to the cobalt salt solution and stir for reaction, then add a silver nitrate solution and continue stirring, and finally add a quenching agent to quench the reaction. The obtained product is washed three times with absolute ethanol and deionized water respectively, centrifuged, collected, and dried, and recorded as CoO@Ag nanozyme.

[0007] In a further embodiment, the cobalt salt is a water-soluble salt such as cobalt nitrate, cobalt sulfate or cobalt chloride; the stabilizer is trisodium citrate; the reducing agent is sodium borohydride, which is pre-cooled before use; the quenching agent is anhydrous ethanol.

[0008] In a further embodiment, the molar ratio of the cobalt salt to silver nitrate is (1-10):1. More preferably, it is 8:1.

[0009] The reaction process involved in the preparation of CoO@Ag nanozyme in the present invention is described as follows:

[0010] First, the NaBH 4 solution acts as a reducing agent to reduce Co 2+ in the cobalt salt solution to Co nanoparticles. Since the Ag + / Ag standard redox potential (0.799 V vs. standard hydrogen electrode (SHE)) is much higher than that of the Co 2+ / Co redox couple (-0.277 V vs. SHE), subsequently, silver nitrate is added to the reaction solution, and the Co nanoparticles are immediately oxidized to Co 2+ , forming CoO. At the same time, Ag + is reduced to Ag and binds to the surface of the CoO nanozyme through electrostatic interaction. During the reaction process, sodium citrate acts as a stabilizer and a dispersant.

[0011] The second aspect of the present invention is to prepare a CoO@Ag-PAN (CAP) fiber membrane. The CoO@Ag nanozyme prepared in the first aspect is used to prepare the CAP fiber membrane, which includes the following steps:

[0012] Disperse polyacrylonitrile powder and CoO@Ag nanozyme in a solvent to obtain a mixed solution; after removing the bubbles in the mixed solution, use electrospinning technology to prepare a functionalized fiber membrane, named CAP thin film. The conditions for electrospinning are: voltage is 12 kV, constant feeding speed is 0.15 mm / min, roller receiver speed is 140 rpm, and the distance between the roller and the needle tip is 15 cm.

[0013] The third aspect of the present invention is to apply the CAP fiber membrane prepared in the second aspect as a bactericidal filtration intermediate layer in a mask, which includes the following steps: press the prepared CAP fiber membrane into shape by mechanical force and replace the middle layer of a common commercial mask with it.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] (1)The CoO@Ag nanozyme provided by the present invention is prepared by a room-temperature reduction method. The required reaction equipment is simple and the reaction conditions are mild. The prepared CoO@Ag nanozyme has excellent antibacterial properties and is suitable for large-scale application production.

[0016] (2)Combining electrospinning technology, the present invention applies the CoO@Ag nanozyme to the CAP fiber membrane and successfully prepares a fiber membrane with excellent inherent antibacterial ability. Its preparation is simple and the raw materials are easy to obtain. It can be prepared in general chemical laboratories and is easy to promote.

[0017] (3)The CAP fiber membrane prepared by the present invention can exhibit excellent real-time antibacterial performance without any auxiliary materials, and can instantaneously generate a large amount of surface-bound singlet oxygen ( ) and hydroxyl radicals ( ), causing bacteria to quickly lose their activity. The CAP mask also has strong inherent antibacterial properties and can kill bacteria almost within 20 minutes. Under simulated sunlight irradiation, it can completely kill bacteria in only 90 seconds, greatly shortening the sterilization time and achieving the real-time protection effect of the mask indoors and outdoors (regardless of the presence or absence of light source). At the same time, the CAP mask maintains a high filtration efficiency and excellent recyclability. It is worth noting that the CAP mask does not heat up significantly even when exposed to sunlight for 3 hours in winter, indicating that it will not cause thermal damage to the human body during normal outdoor use. This study is beneficial to promoting the daily application scenarios of multifunctional masks. Description of the Drawings

[0018] Figure 1 TEM image and EDS image of the CoO@Ag nanozyme prepared in the example;

[0019] Figure 2 Yield test results of singlet oxygen ( 1 O 2 ) and hydroxyl radicals ( ) of the CoO@Ag nanozyme prepared in the example under no light and sunlight simulator irradiation;

[0020] Figure 3 Antibacterial performance test image of the CoO@Ag nanozyme prepared in the example;

[0021] Figure 4 Biocompatibility test image of the CoO@Ag nanozyme prepared in the example;

[0022] Figure 5 SEM image, FT-IR image, stress-strain curve, XRD pattern, and TGA analysis diagram of the PAN and CoO@Ag-PAN (CAP) fiber membranes prepared in the application example;

[0023] Figure 6 Antibacterial performance test diagrams of PAN and CAP3 membranes prepared in the application examples;

[0024] Figure 7 Performance test comparison diagram between the CAP3 membrane mask prepared in the application example and a common commercial mask;

[0025] Figure 8 Photothermal heating infrared images of PAN and CAP3 membranes prepared in the application examples under natural light;

[0026] Figure 9 Antibacterial cycle performance test diagram of the CAP3 membrane prepared in the application example. Detailed implementation manners

[0027] Combined with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention are further described in detail. The specific embodiments described below are only used to explain the present invention and are not used to limit the present invention. The reagents and raw materials used in the following examples are all commercially available products and can be obtained through commercial purchase.

[0028] Example 1

[0029] Prepare CoO@Ag nanozyme with high intrinsic antibacterial ability, including the following steps:

[0030] Dissolve 0.46 mmol of cobalt nitrate hexahydrate in 40 mL of aqueous solution, then add 10 mL of a 2 mM trisodium citrate solution. After magnetic stirring for 30 minutes, quickly add 10 mL of a pre-cooled 8 mM sodium borohydride solution taken out from a 4 °C refrigerator, and continue stirring for 5 minutes. Inject 5 mL of a 2 mg / mL silver nitrate solution and continue the reaction for 10 minutes, then quench the reaction with absolute ethanol. The obtained product is washed three times with absolute ethanol and deionized water respectively, centrifuged and collected, and finally dried in a 60 °C vacuum oven and recorded as CoO@Ag nanozyme.

[0031] Other examples

[0032] In Example 1, the molar ratio of cobalt nitrate hexahydrate to silver nitrate is about 8:1. In other examples, the amounts of cobalt nitrate hexahydrate and silver nitrate are adjusted so that the molar ratios of cobalt nitrate hexahydrate to silver nitrate are 1:1, 4:1, 6:1, and 10:1 respectively. Other processes are the same as those in Example 1. Under different reactant dosages, the corresponding CoO@Ag nanozymes are respectively prepared.

[0033] Product structure characterization and performance testing

[0034] Figure 1These are the TEM and EDS images of the CoO@Ag nanozyme prepared in Example 1. Among them, Figure A is the TEM image of the CoO@Ag nanozyme, Figure B is the EDS image of Co in the CoO@Ag nanozyme, Figure C is the EDS image of Ag in the CoO@Ag nanozyme, and Figure D is the EDS image of O in the CoO@Ag nanozyme. From Figure 1 it can be seen that Ag is mainly distributed on the surface of CoO, and Co, Ag, and O coexist.

[0035] Figure 2 The yields of singlet oxygen ( ) and hydroxyl radicals ([[]] ) of the CoO@Ag nanozymes prepared with cobalt nitrate hexahydrate and silver nitrate in different dosage ratios under dark conditions and under irradiation of a 1 ) solar simulator are shown in Figure 2 . In , Figure A is the yield test result of , and Figure B is the yield test result of Figure 2 . It can be seen from that as the cobalt content increases, the ability to generate ROS gradually increases. When the molar ratio of cobalt nitrate hexahydrate to silver nitrate in the reactants reaches 8:1, the yields of ROS reach the optimum. Even without light, 44.20% of and 16.91% of can be generated within 2 min, while under irradiation of a 1

[0036] Figure 3 solar simulator, the yields increase to 60.35% and 18.69% respectively. After that, although the addition amount of cobalt nitrate hexahydrate continues to increase, the ability to generate ROS decreases. This phenomenon may be attributed to the formation of a more stable CoO and Ag composite structure state at the optimal molar ratio, resulting in the best catalytic performance. Therefore, the following performance tests and the preparation of CAP fiber membranes are carried out at this ratio. 2 These are the antibacterial performance test images of the CoO@Ag nanozyme prepared in Example 1. Escherichia coli and Staphylococcus aureus are selected as the test objects. Among them, Figure A is the digital image of the co - culture of CoO@Ag with Staphylococcus aureus and Escherichia coli under dark conditions, Figure B is the antibacterial efficiency diagram of the co - culture of CoO@Ag with Staphylococcus aureus and Escherichia coli under dark conditions, Figure C is the digital image of the co - culture of CoO@Ag with Staphylococcus aureus and Escherichia coli under irradiation of a 1 W / cm 2 simulated solar light, and Figure D is the antibacterial efficiency diagram of the co - culture of CoO@Ag with Staphylococcus aureus and Escherichia coli under irradiation of a 1 W / cm Figure 3It can be seen from Figures A and B in that: without external light source stimulation, the CoO@Ag nanozyme can achieve 100% antibacterial efficiency within 11 min, indicating its excellent self-antibacterial performance; from Figure 3 It can be seen from Figures C and D in that: under simulated sunlight irradiation of 1 W / cm 2 Almost no viable colonies were observed after 5 min.

[0037] Figure 4 Figure 8 is a biocompatibility test chart of the CoO@Ag nanozyme prepared in the example. A549 cells and Hela cells were selected as the test objects. Among them, Figure A is the staining chart of the co-culture of CoO@Ag and A549 cells, Figure B is the survival rate chart of the co-culture of CoO@Ag and A549 cells, Figure C is the staining chart of the co-culture of CoO@Ag and Hela cells, and Figure D is the survival rate chart of the co-culture of CoO@Ag and Hela cells. Biocompatibility is a key issue in practical applications. The test shows that the CoO@Ag nanozyme has low cytotoxicity, indicating its good biocompatibility.

[0038] Application Example

[0039] Preparation of the functionalized fiber membrane CoO@Ag-PAN (CAP) includes the following steps:

[0040] Disperse 1.2 g of polyacrylonitrile powder and 0.4 mg, 0.8 mg, and 1.6 mg of CoO@Ag nanozyme in 10 mL of N,N-dimethylformamide solution respectively, and stir evenly until the bubbles in the solution completely disappear. Then inject the solution into a 10 mL syringe, connect a 20# stainless steel needle at the needle tip of the syringe, and perform electrospinning. The electrospinning conditions are as follows: the voltage is 12 kV, the constant feeding speed is 0.15 mm / min, the roller receiver speed is 140 rpm, and the distance between the roller and the needle tip is 15 cm. The obtained functionalized nanofiber film is named the CAP film. The CoO@Ag nanozyme content in the CAP film is named CAP1, CAP2, and CAP3 fiber membranes in ascending order. For easy comparison, a pure PAN fiber membrane was also prepared using the same electrospinning process.

[0041] Press the prepared fiber membrane into shape by mechanical force, and a functional mask can be obtained after replacing the middle layer of a common commercial mask with it as a sterilizing filter layer.

[0042] Figure 5SEM images, FT-IR spectra, stress-strain curves, XRD patterns, and TGA analysis diagrams of the prepared PAN and CAP fiber membranes. Among them: Figure A is the SEM image of the PAN and CAP fiber membranes, Figure B is the FT-IR spectrum of the PAN and CAP fiber membranes, Figure C is the stress-strain curve of the PAN and CAP fiber membranes, Figure D is the XRD pattern of the PAN and CAP fiber membranes, and Figure E is the TGA analysis diagram of the PAN and CAP fiber membranes. It can be seen that by electrospinning, CoO@Ag-PAN(CAP) fiber membranes loaded with CoO@Ag nanozymes are prepared. Compared with pure PAN fibers, the fiber diameters of CAP1, CAP2, and CAP3 increase and the surfaces are rougher after loading CoO@Ag, indicating that CoO@Ag is successfully loaded on the surface of PAN fibers. The stress-strain curves show that the CAP1, CAP2, and CAP3 fiber membranes all exhibit better mechanical properties, and the CAP3 membrane has stronger tensile strength. Thermogravimetric analysis also shows that the CAP3 membrane has better thermal stability. All subsequent tests for antibacterial properties use the CAP3 membrane with a CoO@Ag content of 1.6 mg, and the CAP3 membrane is used as a mask model for subsequent applications.

[0043] Figure 6 Antibacterial property test diagrams of the PAN and CAP3 membranes prepared in the application example. Staphylococcus aureus and Escherichia coli are selected as the test objects. Among them: Figure A is the digital image of Staphylococcus aureus cultured under dark conditions, Figure B is the survival rate diagram of Staphylococcus aureus cultured under dark conditions, Figure C is at 1 W / cm 2 Digital image of Staphylococcus aureus cultured under simulated sunlight irradiation, Figure D is at 1 W / cm 2 Survival rate diagram of Staphylococcus aureus cultured under simulated sunlight irradiation, Figure E is the digital image of Escherichia coli cultured under dark conditions, Figure F is the survival rate diagram of Escherichia coli cultured under dark conditions, Figure G is at 1 W / cm 2 Digital image of Escherichia coli cultured under simulated sunlight irradiation, Figure H is at 1 W / cm 2 Survival rate diagram of Escherichia coli cultured under simulated sunlight irradiation. After the antibacterial property evaluation experiment, without external light source stimulation, the CAP3 membrane can kill bacteria within 20 minutes (see the test results in Figures A, B, E, and F in Figure 6 ); under simulated sunlight irradiation, the CAP3 membrane can completely kill bacteria in only 90 s (see the test results in Figures C, D, G, and H in Figure 6 ); it meets the requirements of high-efficiency antibacterial and real-time protection effects (regardless of the presence or absence of light source) for preparing multi-scenario protective materials.

[0044] The prepared spinning membrane was used for mask protection, and performance comparison tests were carried out with ordinary commercial masks. Staphylococcus aureus and Escherichia coli were selected as the test objects, and the results are shown in Figure 7 , where: Figure A is the digital image of Staphylococcus aureus cultured under dark and light conditions with commercial masks and CAP3 masks, Figure B is the digital image of Escherichia coli cultured under dark and light conditions with commercial masks and CAP3 masks, and Figure C is the filtration effect diagram of commercial masks and CAP3 masks for PM 2.5 and PM 10 . It was found that the mask prepared with the CAP3 membrane has excellent antibacterial properties (see Figures A and B in Figure 7 ) and better particulate filtration effect (see Figure C in Figure 7 ).

[0045] To consider the actual application effect, we tested the photothermal heating effect of the CAP3 membrane under natural sunlight and captured images using an infrared camera. The results are shown in Figure 8 . When irradiated by sunlight, the temperature of the PAN membrane increased from the initial temperature of 11.1 °C to 12.4 °C after 3 hours, and the temperature change was 1.3 °C. In contrast, the surface temperature of the CAP3 membrane increased slightly by 3.2 °C. There was no obvious heat generation during the whole process, indicating that it will not cause thermal damage to the human body during normal outdoor use.

[0046] The antibacterial performance cycle test of the CAP3 membrane was carried out, and the results are shown in Figure 9 , where: Figure A is the digital image of Staphylococcus aureus and Escherichia coli cultured under dark conditions, Figure B is the digital image of Staphylococcus aureus and Escherichia coli cultured under light conditions, Figure C is the antibacterial efficiency diagram of Staphylococcus aureus and Escherichia coli cultured under dark conditions, and Figure D is the antibacterial efficiency diagram of Staphylococcus aureus and Escherichia coli cultured under light conditions. It was found that within 5 cycles, the antibacterial effect of the CAP3 membrane was hardly affected under both light and dark conditions, indicating that the CoO@Ag nanozyme will not easily leak from the fiber surface, further ensuring the safety of the wearer.

[0047] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing CoO@Ag nanozyme, characterized in that: The following steps are involved: The cobalt salt and the stabilizer are dissolved in water to obtain a cobalt salt solution, a reducing agent is added to the cobalt salt solution and stirred for reaction, then a silver nitrate solution is added and stirred continuously, and finally a quencher is added to quench the reaction, and the obtained product is washed and dried and recorded as CoO@Ag nanozyme; The stabilizer is trisodium citrate; the reducing agent is sodium borohydride, and the sodium borohydride is pre-cooled before use.

2. The method for preparing CoO@Ag nanozyme according to claim 1, characterized in that: The cobalt salt is cobalt nitrate, cobalt sulfate or cobalt chloride.

3. The method for preparing CoO@Ag nanozyme according to claim 1, characterized in that: The molar ratio of the cobalt salt to silver nitrate is (1-10):

1.

4. The method for preparing CoO@Ag nanozyme according to claim 1, characterized in that: The quenching agent is anhydrous ethanol.

5. A CoO@Ag nanozyme, characterized in that: The invention discloses a novel nanostructured carbon foam prepared by the preparation method described in any one of claims 1 to 4.

6. A method for preparing a functionalized fiber membrane, characterized in that: The following steps are involved: The polyacrylonitrile powder and the CoO@Ag nanozyme as claimed in claim 5 are dispersed in a solvent to obtain a mixed solution; after removing the bubbles in the mixed solution, a functionalized fiber membrane is prepared by using an electrospinning technology.

7. The functionalized fiber membrane prepared by the preparation method according to claim 6 is used as a sterilization and filtration intermediate layer in a mask.

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