A method for preparing a selenium-copper oxide-laponite composite nanoscale enzyme from a plant source composite and antibacterial applications thereof
A selenium-cuprous oxide-lithium saponite composite nanozyme was prepared by using plant-derived complexes such as quinoa husk extract through a green synthesis method. This solved the problems of toxicity and efficiency in nanozyme synthesis, achieving high-efficiency antibacterial effect and stability, and expanding the application of antibacterial therapy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LANZHOU INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2026-02-11
- Publication Date
- 2026-06-09
AI Technical Summary
Existing nanozyme synthesis methods use toxic chemicals, are complex and costly, and single-component nanozymes have limited catalytic efficiency, are prone to aggregation, and are difficult to effectively combat multidrug-resistant bacterial infections.
A plant-derived complex of quinoa husk extract, ascorbic acid, and aloe-emodin was used as a reducing agent and stabilizer. Selenium-cuprous oxide nanoparticles were loaded onto peeled lithium saponite nanosheets to form a stable core-shell heterojunction structure, thus achieving the green synthesis of highly efficient nanozymes.
The prepared composite nanozyme has a high specific surface area, uniform nanostructure and excellent peroxidase-like activity. It can efficiently catalyze the production of antibacterial reactive oxygen species, significantly resist multidrug-resistant bacteria, and is not prone to inducing drug resistance, showing broad application prospects.
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Abstract
Description
Technical Field
[0001] This invention relates to the fields of nanomaterials technology and antibacterial agents, and particularly to a method for preparing selenium-cuprous oxide-lithium saponite composite nanoenzymes using plant-derived complexes, and the application of the composite nanoenzymes in the antibacterial treatment of drug-resistant bacteria. Background Technology
[0002] In recent years, the emergence and spread of multidrug-resistant strains due to antibiotic overuse has become a major challenge in global public health. According to the World Health Organization, drug-resistant bacterial infections cause millions of deaths annually, and this number continues to rise. Traditional antibiotic development is lagging far behind the rate of bacterial resistance evolution, making the development of novel antimicrobial strategies an urgent priority.
[0003] Nanozymes are a class of nanomaterials with enzyme-mimicking activity, capable of catalyzing the production of highly reactive reactive oxygen species, which disrupt bacterial cell structure and thus kill bacteria. Compared to natural enzymes, nanozymes offer advantages such as high stability, low cost, and large-scale production capability. Compared to conventional antibiotics, nanozymes disrupt bacterial structure through a physicochemical multi-target mechanism, making them less likely to induce drug resistance, thus providing a new approach to combating drug-resistant bacteria. Among various nanozymes, copper-based nanomaterials have attracted widespread attention due to their excellent peroxidase-like activity and broad-spectrum antibacterial properties. Journal of Inorganic Materials, 2023, 38(05): 489- 502. Cuprous oxide is a typical p-type semiconductor material with good catalytic performance and bioactivity. Selenium is an essential trace element for the human body, possessing antioxidant and immunomodulatory functions; selenium nanomaterials also exhibit certain bioactivity and catalytic performance. However, single-component nanozymes often have limited catalytic efficiency, and nanoparticles are prone to aggregation, affecting their activity and stability.
[0004] Lithium saponite is a synthetic silicate clay mineral with a layered structure. After exfoliation, nanosheets can be obtained, which have a large specific surface area and strong ion exchange capacity, making them excellent carriers for nanomaterials. Chinese Journal of Tissue Engineering Research, 2021 25(10):1622-1627. Lithium saponite nanosheets can effectively load nanoparticles, preventing their aggregation and improving dispersibility and stability. Previous studies have used lithium saponite as a carrier for antibacterial agents, such as chitosan quaternary ammonium salt-modified organolithium saponite-based antibacterial agents. magnificent Journal of Nanjing University of Science and Technology (Natural Science Edition), 2025, 53(8): 158-166. ) and Ag / lithium saponite composite antibacterial agent ( Micro&Nano Letters 14.5 (2019): 531-533. These studies demonstrate the feasibility of lithium saponite as a carrier for antibacterial materials.
[0005] Currently, most nanozyme synthesis methods are chemical methods, often using strong reducing agents and stabilizers, which pose potential toxicity and environmental risks. Green synthesis methods utilize plant extracts as reducing agents and stabilizers, offering advantages such as environmental friendliness and good biocompatibility. Industrial Microbiology, 2025, 55(05):219-222. The active ingredients in plant extracts, such as polyphenols and flavonoids, can not only reduce metal ions but also functionalize the surface of nanomaterials, enhancing their bioactivity and stability. Quinoa husks, a byproduct of quinoa processing, are rich in polyphenolic compounds, saponins, alkaloids, polysaccharides, and other active ingredients, possessing certain functions in reducing and stabilizing nanoparticles. Ascorbic acid is an excellent reducing agent in natural product fermentation, promoting the formation of nano-selenium. Aloe-emodin, an anthraquinone compound, can form complexes with selenium ions or atoms, facilitating the regulation of nanoparticle nucleation and growth. The synthesis of nanozymes using complexes of various natural products as reducing and stabilizing agents, enabling the efficient synthesis of size-controllable nanozymes, has not yet been reported. Summary of the Invention
[0006] The purpose of this invention is to provide a green and efficient method for preparing selenium-cuprous oxide-lithium saponite composite nanozymes from plant-derived complexes, overcoming the technical defects of existing chemical synthesis methods, such as the use of toxic reagents, complex processes, and high costs.
[0007] Another object of the present invention is to provide a composite nanozyme prepared by the above method, which has a high specific surface area, a uniform nanostructure and excellent peroxidase-like activity.
[0008] Another objective of this invention is to provide the application of the above-mentioned composite nanozyme in the antibacterial treatment of drug-resistant bacteria, thereby expanding its application potential in the biomedical field.
[0009] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing selenium-cuprous oxide-lithium saponite composite nanozymes from plant-derived complexes, comprising the following steps: (1) Carrier treatment: Lithium saponite was dispersed in water, the pH was adjusted to 9-11 (alkaline conditions), and after oil bath heating and ultrasonic treatment, it was centrifuged, washed and redispersed to obtain lithium saponite nanosheet suspension; During the lithium saponite flake removal process, the oil bath heating temperature is 60~80℃ and the heating time is 2~6 hours; the ultrasonic treatment power is 300~800W and the ultrasonic treatment time is 30~120 minutes.
[0010] (2) Preparation of reducing agent: Quinoa hull powder was mixed with ethanol-water mixed solution, heated and refluxed for extraction, and filtered to obtain quinoa hull extract; ascorbic acid and aloe-emodin were dissolved in anhydrous ethanol, mixed with quinoa hull extract in proportion, and stirred evenly to obtain plant-derived composite reducing agent. The solid-liquid ratio of the quinoa husk powder to the ethanol-water mixture is 1:10 to 1:30 g / mL; the volume concentration of ethanol in the ethanol-water mixture is 0% to 70%; the temperature of the heating and reflux extraction is 55 to 70°C, and the time is 2 to 4 hours; the amounts of ascorbic acid and aloe-emodin added are 0.1% to 10% and 0.01% to 0.1% of the mass of the quinoa husk extract, respectively.
[0011] (3) Preparation of composite nanozyme: The lithium saponite nanosheet suspension obtained in step (1) is placed in a reaction vessel, and copper salt solution and plant-derived composite reducing agent obtained in step (2) are added. After stirring evenly, the pH is adjusted to alkaline and the reaction is carried out at 40~70℃ for 1~5 hours. Then, selenium source solution is added and the reaction is continued at 40~70℃ for 2~8 hours. After the reaction is completed, the product is collected by centrifugation, washed with deionized water and anhydrous ethanol in turn to remove unreacted impurities and reagents. Finally, after drying, a brownish-red powder of selenium-cuprous oxide-lithium saponite composite nanozyme is obtained.
[0012] The copper salt is selected from at least one of copper acetate, copper nitrate, copper chloride, or copper sulfate; the selenium source is sodium selenite; the molar ratio of copper to selenium is 1:0.5 to 1:2, and the mass ratio of copper to lithium saponite nanosheets is 1:4 to 1:20. This ratio ensures uniform loading of nanoparticles and the formation of stable heterojunctions; the pH is adjusted to 10 to 12 to further optimize the reaction conditions; the mass ratio of the plant-derived composite reducing agent to copper is 50:1 to 200:1 to ensure sufficient reduction of metal ions; the drying treatment can be carried out by oven drying or vacuum drying, with the drying temperature preferably at 40 to 80°C for 12 to 24 hours to avoid high temperature damage to the structure and activity of the composite nanoenzyme.
[0013] This invention provides a selenium-cuprous oxide-lithium saponite composite nanozyme prepared by the above method. The composite nanozyme has a core-shell structure, with lithium saponite nanosheets as the core and selenium-cuprous oxide nanoparticles uniformly loaded on the surface of the core as the shell. The particle size of the selenium-cuprous oxide nanoparticles is 2~10 nanometers, and a tight heterojunction structure is formed between selenium and cuprous oxide.
[0014] The composite nanozyme exhibits peroxidase-like activity and can catalyze the decomposition of hydrogen peroxide to generate hydroxyl radicals; the composite nanozyme maintains high enzyme activity within the pH range of 3 to 7.
[0015] This invention provides the application of the above-mentioned selenium-cuprous oxide-lithium saponite composite nanoenzyme in the preparation of antibacterial agents. The antibacterial agent is used to treat or prevent infections caused by drug-resistant bacteria. The drug-resistant bacteria include at least one of methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococci, Enterobacteriaceae producing extended-spectrum β-lactamases, multidrug-resistant Pseudomonas aeruginosa, and multidrug-resistant Acinetobacter baumannii. The antibacterial agent is a wound dressing, a medical antibacterial coating, or an anti-infective drug preparation.
[0016] The synthesis mechanism of the plant-derived complex for synthesizing selenium-cuprous oxide-lithium saponite composite nanoenzymes described in this invention is as follows: First, lithium saponite is treated by heating and ultrasonic exfoliation under alkaline conditions to disrupt its interlayer forces, obtaining lithium saponite nanosheet carriers with high specific surface area and negative charge, providing sufficient active sites for subsequent nanoparticle loading; then, the plant-derived complex composed of polyphenols, saponins, alkaloids, and other active compounds from quinoa husk extract, as well as ascorbic acid and aloe-emodin, serves as a reducing agent and stabilizer. Its active functional groups release electrons during the reaction, enabling efficient reduction of Cu. The invention utilizes Cu⁺ and SeO₃²⁻ to simultaneously coat newly formed nanoparticles in situ, effectively preventing nanoparticle aggregation and improving their dispersibility and stability. Aloe-emodin can form a complex with selenium ions and slow down the reduction process, which, from the perspectives of generation rate and steric hindrance, facilitates the formation of uniformly sized and narrowly distributed selenium nanoparticles, avoiding problems such as size inhomogeneity and structural instability caused by rapid, large-scale nucleation. Finally, the Cu⁺ and Se species generated during reduction preferentially undergo heterogeneous nucleation and interfacial coupling on the surface of lithium saponite nanosheets, forming a heterojunction structure in which selenium and cuprous oxide are tightly bonded. This invention achieves a synergistic effect of carrier engineering, green reduction, and interfacial effects. The constructed composite nanostructure significantly enhances the catalytic activity of simulated peroxidase, thereby efficiently catalyzing the generation of antibacterial reactive oxygen species and improving the antibacterial effect.
[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The synthesis method is green, environmentally friendly, efficient and controllable: This invention uses a plant-derived complex formed by quinoa husk extract, aloe-emodin and ascorbic acid as a reducing agent and stabilizer to replace the strong toxic reducing agent used in traditional chemical synthesis, thereby reducing the use of toxic chemicals, reducing environmental risks, and having good biocompatibility; at the same time, the three plant-derived components work synergistically, which not only improves the reduction efficiency compared with single plant extracts, but also effectively controls the size and morphology of nanoparticles, making the nanoparticles uniform in size and well dispersed, and easy to scale up production.
[0018] (2) The composite nanozyme has a stable structure and high catalytic activity: The present invention uses peeled lithium saponite nanosheets as a carrier to load selenium-cuprous oxide nanoparticles to form a stable core-shell heterojunction structure. The high specific surface area and layered structure of the lithium saponite nanosheets can effectively prevent the aggregation of selenium-cuprous oxide nanoparticles and expose more active sites. At the same time, the heterojunction structure formed between selenium and cuprous oxide significantly enhances the peroxidase activity of the composite nanozyme, which can efficiently catalyze hydrogen peroxide to generate a large number of hydroxyl radicals and improve antibacterial efficiency.
[0019] (3) Significant antibacterial effect and not easy to induce drug resistance: The composite nanozyme prepared in this invention has a significant antibacterial effect on a variety of multidrug-resistant bacteria through multiple mechanisms such as catalytic generation of reactive oxygen species, physical destruction of bacterial cell membranes, and release of a small amount of metal ions. Moreover, the antibacterial mechanism is multi-target action, which is not easy to induce drug resistance in bacteria, thus solving the drug resistance problem caused by the abuse of traditional antibiotics.
[0020] (4) Broad application prospects: This composite nanozyme has good biocompatibility and environmental friendliness. It can be used to prepare wound dressings, medical antibacterial coatings or anti-infective drug preparations. It has broad application prospects in antibacterial therapy, wound healing, biomedical engineering and other fields. At the same time, it realizes the high-value utilization of quinoa husk by-products and reduces production costs. Attached Figure Description
[0021] Figure 1 This is a transmission electron microscope (TEM) image of the selenium-cuprous oxide-lithium saponite composite nanozyme prepared in Example 1 of this invention. Figure 2 These are the results of the simulated peroxidase activity assay of the composite nanozyme prepared in Example 1 of this invention; Figure 3 This is a diagram illustrating the antibacterial effect of the composite nanozyme prepared in Example 1 of this invention. Detailed Implementation
[0022] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples, but the scope of protection of the present invention is not limited thereto.
[0023] Example 1 (1) Preparation of lithium saponite nanosheets: Weigh 1.0 g of lithium saponite powder and disperse it in 100 mL of deionized water. Adjust the pH to 10.5 using 1 mol / L sodium hydroxide solution. Heat and stir the mixture in an 80°C oil bath for 4 hours. Then, sonicate the suspension at 500 W for 60 minutes. Wash the resulting suspension by centrifugation at 10,000 rpm and redisperse it with deionized water. Make up the volume to 100 mL to obtain a lithium saponite nanosheet suspension for later use.
[0024] (2) Preparation of plant-derived compound reducing agent: Take 20 g of dried quinoa hull powder and mix it with 400 mL of 25% (v / v) ethanol-water solution (solid-liquid ratio of 1:20). Heat and reflux at 60°C for 3 hours, cool and filter to obtain quinoa hull extract. Separately weigh 0.5 g of ascorbic acid and 0.5 mg of aloe-emodin, dissolve them in an appropriate amount of anhydrous ethanol, and mix them with the above quinoa hull extract after complete dissolution to obtain plant-derived compound reducing agent, which is stored at 4°C for later use.
[0025] (3) Synthesis of composite nanozyme: 50 mL of the above lithium saponite nanosheet suspension (containing approximately 0.5 g of lithium saponite) was measured into a three-necked flask. 0.05 g (calculated as copper) of copper nitrate (Cu(NO3)2·3H2O) dissolved in 5 mL of water was added. Then, 5 mL of plant-derived composite reducing agent (the mass ratio of reducing agent to copper was approximately 100:1) was added. The pH of the reaction system was adjusted to 11.0 with 1 mol / L sodium hydroxide solution. The mixture was placed in a 60°C water bath and stirred continuously for 3 hours. Then, 0.13 g of sodium selenite (Na2SeO3, with a molar ratio of 1:1 to copper) dissolved in 5 mL of water was added. The reaction was continued at 60°C for 5 hours. After the reaction was completed, the product was collected by centrifugation, washed three times each with deionized water and anhydrous ethanol, and finally dried in a 45°C vacuum drying oven for 20 hours to obtain a brownish-red powdered selenium-cuprous oxide-lithium saponite composite nanozyme.
[0026] Example 2 (1) Preparation of lithium saponite nanosheets: Same as in Example 1.
[0027] (2) Preparation of plant-derived compound reducing agent: Take 15 g of quinoa husk powder, mix it with 225 mL of 60% ethanol-water solution (solid-liquid ratio 1:15), reflux extract at 60°C for 3 hours, and filter to obtain the extract. Weigh 0.5 g of ascorbic acid and 5 mg of aloe-emodin, dissolve them in anhydrous ethanol, and mix them with the extract to obtain the compound reducing agent.
[0028] (3) Synthesis of composite nanozyme: Take 50 mL of lithium saponite nanosheet suspension (containing 0.5 g of lithium saponite). Add 0.1 g (calculated as copper element) of copper sulfate (CuSO4·5H2O) solution (copper to lithium saponite mass ratio is approximately 1:3). Add 5 mL of plant-derived composite reducing agent (reducing agent to copper element mass ratio is approximately 50:1) and adjust the pH to 10.5. After reacting at 55°C for 2 hours, add 0.325 g of sodium selenite solution (copper-selenium molar ratio 1:1.2) and continue the reaction for 6 hours. After the reaction is completed, collect the product by centrifugation, wash it 3 times each with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 50°C for 16 hours to obtain brownish-red powdered selenium-cuprous oxide-lithium saponite composite nanozyme.
[0029] Example 3 (1) Preparation of lithium saponite nanosheets: Adjust the pH to 9.0, heat in an oil bath at 70°C for 5 hours, sonicate at 400W for 90 minutes, and then perform the same subsequent treatment as in Example 1.
[0030] (2) Preparation of plant-derived compound reducing agent: Take 25 g of quinoa husk powder, mix it with 250 mL of 40% ethanol-water solution (solid-liquid ratio 1:10), reflux at 55°C for 4 hours, and filter to obtain the extract. Weigh 0.018 g of ascorbic acid and 18 mg of aloe-emodin to prepare a compound reducing agent.
[0031] (3) Synthesis of composite nanozyme: Take 50 mL of lithium saponite nanosheet suspension. Add 0.15 g (calculated as copper element) of copper chloride (CuCl2·2H2O) solution (copper to lithium saponite mass ratio 1:10). Add 18 mL of plant-derived composite reducing agent (reducing agent to copper element mass ratio 120:1) and adjust pH to 10.0. After reacting at 45°C for 5 hours, add 0.41 g of sodium selenite solution (copper-selenium molar ratio 1:0.5) and continue the reaction for 3 hours. After the reaction is completed, collect the product by centrifugation, wash it 3 times each with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60°C for 12 hours to obtain brownish-red powdered selenium-cuprous oxide-lithium saponite composite nanozyme.
[0032] Example 4 (1) Preparation of lithium saponite nanosheets: Adjust the pH to 11.0, heat in an oil bath at 75°C for 3 hours, sonicate at 700W for 30 minutes, and then perform the same subsequent treatment as in Example 1.
[0033] (2) Preparation of plant-derived compound reducing agent: Take 25 g of quinoa husk powder, mix it with 250 mL of 30% ethanol-water solution (solid-liquid ratio 1:25), reflux at 70°C for 2 hours, and filter to obtain the extract. Weigh 0.3 g of ascorbic acid and 15 mg of aloe-emodin to prepare a compound reducing agent.
[0034] (3) Synthesis of composite nanozyme: Take 50 mL of lithium saponite nanosheet suspension. Add 0.2 g (calculated as copper element) of copper acetate solution (copper to lithium saponite mass ratio 1:10). Add 30 mL of plant-derived composite reducing agent (reducing agent to copper element mass ratio 150:1) and adjust pH to 12.0. After reacting at 70°C for 1 hour, add 0.81 g of sodium selenite solution (copper-selenium molar ratio 1:1.5) and continue the reaction for 2 hours. After the reaction is completed, collect the product by centrifugation, wash it 3 times each with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 40°C for 24 hours to obtain brownish-red powdered selenium-cuprous oxide-lithium saponite composite nanozyme.
[0035] Example 5 (1) Preparation of lithium saponite nanosheets: Adjust the pH to 10.0, heat in an oil bath at 80°C for 5 hours, sonicate at 400W for 90 minutes, and then perform the same subsequent treatment as in Example 1.
[0036] (2) Preparation of plant-derived compound reducing agent: Take 25 g of quinoa husk powder, mix with 250 mL of 40% ethanol-water solution (solid-liquid ratio 1:10), reflux at 65°C for 2.5 hours, and filter to obtain the extract. Weigh 2.5 g of ascorbic acid and 0.05 g of aloe-emodin to prepare a compound reducing agent.
[0037] (3) Synthesis of composite nanozyme: Take 50 mL of lithium saponite nanosheet suspension and add 0.25 g (calculated as copper element) of copper nitrate solution. Add 50 mL of plant-derived composite reducing agent (reducing agent to copper element mass ratio of 200:1) and adjust pH to 11.0. After reacting at 60°C for 4 hours, add 1.35 g of sodium selenite solution (copper-selenium molar ratio 1:2) and continue the reaction for 8 hours. After the reaction is completed, collect the product by centrifugation, wash it 3 times each with deionized water and anhydrous ethanol, and finally dry it in a vacuum drying oven at 60°C for 12 hours to obtain brownish-red powdered selenium-cuprous oxide-lithium saponite composite nanozyme.
[0038] Performance testing 1. Structural characterization: Figure 1 The images show transmission electron microscopy (TEM) images of lithium saponite before and after peeling, as well as TEM images of the selenium-cuprous oxide-lithium saponite composite nanozyme prepared in Example 1 of this invention. The results show that, compared to the original lithium saponite, the peeled lithium saponite exhibits a monolayer dispersion. The TEM images of the selenium-cuprous oxide-lithium saponite composite nanozyme show that the surface of the layered lithium saponite is loaded with uniformly distributed selenium-cuprous oxide composite nanoparticles with small particle sizes (2-10 nm) and good dispersion. Clear lattice fringes and interfaces can be observed in the high-resolution images, confirming that a tight heterojunction structure has formed between selenium and cuprous oxide.
[0039] 2. Simulated Enzyme Activity Assay: Using TMB (3,3',5,5'-tetramethylbenzidine) as the chromogenic substrate and hydrogen peroxide (H2O2) as the reactant, the peroxidase-like (POD) activity of the product obtained in Example 1 was tested. The results are as follows: Figure 2 As shown, in the presence of hydrogen peroxide (H2O2), this material can catalyze the color reaction of TMB substrate, exhibiting a characteristic absorption peak at 652 nm; however, this characteristic peak was not observed in the blank control group without added H2O2. This result confirms that the composite material of the present invention can effectively catalyze the generation of hydroxyl radicals (•OH) from H2O2, thereby oxidizing TMB to produce a color reaction, and possesses significant POD-like enzyme activity.
[0040] 3. Antibacterial Performance Test: Methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase-producing Escherichia coli (ESBL-E. coli) were selected as representative drug-resistant bacteria. The antibacterial effect of the product obtained in Example 1 was evaluated by plate count method. The results are as follows: Figure 3 As shown, in the presence of low concentrations of H2O2, this composite nanozyme exhibits activity against MRSA and ESBL- E. coli All exhibited significant bactericidal effects (antibacterial rate exceeding 99%). This is mainly attributed to their peroxidase-like activity, which catalyzes the generation of a large number of hydroxyl radicals (•OH) from H₂O₂, while simultaneously causing physical damage to the bacterial cell membrane, thus achieving synergistic antibacterial effects. These results confirm the material's potential application in combating multidrug-resistant bacteria.
[0041] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for preparing selenium-cuprous oxide-lithium saponite composite nanozymes from plant-derived complexes, characterized in that, Includes the following steps: (1) Carrier treatment: Lithium saponite was dispersed in water, the pH was adjusted to alkaline, and after heating and ultrasonic treatment, it was centrifuged, washed and dispersed to obtain a lithium saponite nanosheet suspension. (2) Preparation of reducing agent: Quinoa hull powder was heated and refluxed with ethanol-water mixture to extract quinoa hull extract; ascorbic acid and aloe-emodin were dissolved in anhydrous ethanol and mixed with quinoa hull extract to obtain plant-derived composite reducing agent. (3) Preparation of composite nanoenzyme: The lithium saponite nanosheet suspension obtained in step (1), copper salt solution and plant-derived composite reducing agent obtained in step (2) are mixed, the pH is adjusted to alkaline and reacted at 40~70℃ for 1~5 hours, then the selenium source solution is added and the reaction is continued at 40~70℃ for 2~8 hours. After the reaction is completed, the selenium-cuprous oxide-lithium saponite composite nanoenzyme is obtained by centrifugation, washing and drying.
2. The method according to claim 1, characterized in that, In step (1), the pH is adjusted to 9-11; the heating is performed in an oil bath at 60-80°C for 2-6 hours; the ultrasonic treatment has a power of 300-800W and a duration of 30-120 minutes.
3. The method according to claim 1, characterized in that, In step (2), the solid-liquid ratio of the quinoa husk powder to the ethanol-water mixture is 1:10~1:30 g / mL; the volume concentration of ethanol in the ethanol-water mixture is 0%~70%; the temperature of the heating and reflux extraction is 55~70°C, and the time is 2~4 hours; the amounts of ascorbic acid and aloe-emodin added are 0.1%~10% and 0.01%~0.1% of the mass of the quinoa husk extract, respectively.
4. The method according to claim 1, characterized in that, In step (3), the copper salt is selected from at least one of copper acetate, copper nitrate, copper chloride or copper sulfate; the selenium source is sodium selenite; the molar ratio of copper to selenium is 1:0.5 to 1:2; and the mass ratio of copper to lithium saponite nanosheets is 1:4 to 1:
20.
5. The method according to claim 1, characterized in that, In step (3), the pH is adjusted to 10-12; the mass ratio of the plant-derived composite reducing agent to copper is 50:1-200:
1.
6. A selenium-cuprous oxide-lithium saponite composite nanozyme prepared by the method according to any one of claims 1-5, characterized in that, This composite nanozyme has a core-shell structure, with lithium saponite nanosheets as the core and selenium-cuprous oxide nanoparticles uniformly loaded on the surface of the carrier as the shell. The particle size of the selenium-cuprous oxide nanoparticles is 2~10 nanometers, and a tight heterojunction structure is formed between selenium and cuprous oxide.
7. The selenium-cuprous oxide-lithium saponite composite nanoenzyme according to claim 6, characterized in that, The composite nanozyme exhibits peroxidase-like activity and can catalyze the decomposition of hydrogen peroxide to generate hydroxyl radicals; the composite nanozyme maintains high enzyme activity within the pH range of 3 to 7.
8. The application of the selenium-cuprous oxide-lithium saponite composite nanozyme as described in claim 6 in the preparation of antibacterial agents.
9. The application according to claim 8, characterized in that, The antibacterial agent is used to treat or prevent drug-resistant bacterial infections; the drug-resistant bacteria include at least one of methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, Enterobacteriaceae bacteria producing extended-spectrum β-lactamase, multidrug-resistant Pseudomonas aeruginosa, and multidrug-resistant Acinetobacter baumannii.
10. The application according to claim 8 or 9, characterized in that, The antibacterial agent is used to prepare wound dressings, medical antibacterial coatings, or anti-infective drug preparations.