Metal-mof nanozyme and preparation method and application thereof

Abstract

The application discloses a metal-MOF nano-enzyme, a preparation method and application thereof, and aims to provide a metal-MOF nano-enzyme with hydrogen peroxide mimetic enzyme activity, which can significantly improve the antibacterial effect on E. coli and S. aureus and can be applied to E. coli and S. aureus bacteriostatic agents. The technical scheme is that metal salt solution is added into 2-methyl imidazole solution, and metal-MOF nano-enzyme is synthesized through ultrasonic water bath. The application belongs to the technical field of nano-mimetic enzymes and medical antibacterial technology.

Description

Technical Field

[0001] This invention discloses a nanozyme, specifically a metal-MOF nanozyme. This invention also discloses the preparation method and application of the metal-MOF nanozyme, belonging to the field of nano-mimetic enzyme and medical antibacterial technology. Background Technology

[0002] Diseases caused by bacterial infections are a global public health problem. It is estimated that millions of people die from bacterial infections each year. Antibiotics are the traditional method for treating infectious bacteria, but their overuse has led to increasing bacterial resistance and even the emergence of "superbugs." Therefore, there is an urgent need to find new antibacterial agents.

[0003] Nanoenzymes, a class of nanomaterials with reaction mechanisms similar to natural enzymes, have attracted considerable attention in antibacterial therapy. Among them, functional nanoparticles with peroxidase-like properties generate reactive oxygen species (ROS) during catalysis that act on cell membranes, effectively killing bacteria and making them ideal antibacterial materials. MOF-based nanoenzymes offer many advantages, such as high stability, low cost, and ease of storage. According to literature reports, MOF nanoenzymes with copper ions or copper ion clusters as active centers possess themselves the catalytic activity of enzymes, especially exhibiting excellent peroxidase-mimicking activity.

[0004] Chinese patent CN 111330643 A discloses an ultrasonic synthesis method for different monometallic and bimetallic two-dimensional MOF nanozymes and their applications. The method includes the following steps:

[0005] (1) Dissolve terephthalic acid in a solvent by ultrasonication to obtain solution A, and then dissolve one or two different metal salts in solution A by ultrasonication to obtain mixed solution B;

[0006] (2) Quickly inject the deprotonated solvent into the mixed solution B and stir for 5 min at room temperature to obtain a uniform colloidal suspension mixed solution C;

[0007] (3) The colloidal suspension mixture C was placed into a polytetrafluoroethylene tube, the tube was sealed, and ultrasonication was performed at a temperature of 20–50℃ and an ultrasonic power of 30–200 kHz for 0.5–24 h. After the reaction, the mixture was centrifuged at 5000–15000 r / min, washed with ethanol 3–5 times, and dried. The mixture was then kept at 30–90℃ under nitrogen or vacuum conditions to obtain different single-metal and bimetallic two-dimensional MOF nanozyme materials. This method uses a mixed solution of N,N-dimethylformamide (DMF), deionized water, and anhydrous ethanol in a certain volume ratio to dissolve terephthalic acid, and ethanol is used for the final washing. Its disadvantage is that it uses organic solvents, which causes some environmental pollution. Summary of the Invention

[0008] To address the above shortcomings, the present invention aims to provide a metal-MOF nanozyme that can significantly improve the antibacterial effect against Staphylococcus aureus and Escherichia coli.

[0009] The second objective of this invention is to provide a method for preparing metal-MOF nanozymes, which is green and environmentally friendly, and saves production costs and energy consumption.

[0010] A third objective of this invention is to provide applications of the aforementioned metal-MOF nanozymes.

[0011] Therefore, the first technical solution provided by this invention is:

[0012] A method for preparing metal-MOF nanozymes involves adding a metal salt solution to a 2-methylimidazole solution to synthesize metal-MOF nanozymes.

[0013] Furthermore, the preparation method of the above-mentioned metal-MOF nanozyme includes the following steps in sequence:

[0014] Step (1): Dissolve 2-methylimidazole, hexadecyltrimethylammonium bromide, and the metal salt in ultrapure water respectively;

[0015] Step (2): Add the dissolved 2-methylimidazole solution to the hexadecyltrimethylammonium bromide aqueous solution, sonicate for 5-20 min, add the metal salt solution, and continue sonication in a water bath for 1-5 h to obtain the reaction solution;

[0016] Step (3): The reactants obtained in step 2 are centrifuged, washed with ultrapure water, and dried to obtain the metal-MOF nanozyme.

[0017] Furthermore, in the above-mentioned method for preparing metal-MOF nanozymes, the metal salt is a copper salt, or a combination of copper salt and zinc salt.

[0018] Furthermore, in the above-mentioned method for preparing metal-MOF nanozymes, the molar ratio of zinc salt to copper salt is 1:4 to 1:20.

[0019] Furthermore, in the above-mentioned method for preparing metal-MOF nanozymes, the copper salt is one or more of copper chloride, copper nitrate, or copper sulfate; and the zinc salt solution is one or more of zinc chloride, zinc nitrate, or zinc sulfate.

[0020] Furthermore, in the above-mentioned method for preparing metal-MOF nanozymes, the concentration of 2-methylimidazole dissolved in ultrapure water is 1-100 mol / L; and the concentration of the metal salt dissolved in ultrapure water is 10-300 mmol / L.

[0021] Furthermore, in the above-mentioned method for preparing metal-MOF nanozymes, the ultrasonic power is 60-100W and the water bath temperature is 37-80℃.

[0022] Furthermore, in the above-mentioned method for preparing metal-MOF nanozymes, step 3) involves centrifuging to obtain a precipitate, washing it 3-6 times with ultrapure water, drying it in an oven at a temperature of 50-100℃, and then drying it to obtain the metal-MOF nanozyme.

[0023] The second technical solution provided by the present invention is a metal-MOF nanozyme, wherein the metal-MOF nanozyme is a Cu-Zn-MOF nanozyme or Cu-MOF, and is prepared by the preparation method provided by the first technical solution.

[0024] The third technical solution provided by this invention is the application of the aforementioned metal-MOF nanozyme as an antibacterial agent against Escherichia coli and Staphylococcus aureus.

[0025] This invention employs a green, environmentally friendly, energy-saving, and inexpensive ultrasonic hydrothermal process to prepare bipyramidal Cu-MOFs with a unique morphology. The prepared bipyramidal nanoparticles exhibit uniform morphology, with an average length of 300-500 nm and a width of 150-250 nm. Utilizing the bipyramidal morphology of Cu-MOFs, this invention can physically puncture bacterial cell membranes and release low-toxicity, highly biocompatible Cu in phosphate buffer solution. 2+ Metal ions induce bacteria to produce endogenous ROS, thereby achieving a good antibacterial effect. It has a killing effect on Staphylococcus aureus and Escherichia coli. At 80 μg / mL, the antibacterial effect on Escherichia coli and Staphylococcus aureus reaches 99%.

[0026] This invention employs a green, environmentally friendly, energy-saving, and inexpensive ultrasonic hydrothermal process to prepare a novel bimetallic Cu-Zn-MOF with uniform morphology and a size of 4-8 μm (micrometer scale). It releases two low-toxicity, highly biocompatible Cu ions in phosphate buffer solution. 2+ and Zn 2+ It has hydrogen peroxide-like enzyme activity and can kill Staphylococcus aureus and Escherichia coli. It can be used for antibacterial treatment of common infectious bacteria such as Staphylococcus aureus and Escherichia coli.

[0027] Based on the overall inventive concept, this invention also utilizes the principle that Cu-Zn-MOF and Cu-MOF possess hydrogen peroxide-like enzyme activity, which can catalyze the oxidation of TMB from colorless to blue by H2O2. Quantitative determination of H2O2 is achieved through colorimetric analysis using a UV-Vis spectrophotometer. Furthermore, based on the reaction where glucose is oxidized by glucose oxidase to produce H2O2 and glucuronic acid, the content of generated H2O2 reflects the glucose content in the sample. This characteristic is combined with the H2O2 detection system of this invention to achieve quantitative detection of glucose.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. The Cu-Zn-MOF of the present invention is a second metal Cu 2+ Cu-MOF is a novel and specific micron-scale material synthesized under high doping. It is a novel and specific bipyramidal nanomaterial with a simple, easy-to-operate, and environmentally friendly preparation process.

[0030] 2. The Cu-MOF and Cu-Zn-MOF of the present invention have catalase-like activity, which can catalyze the oxidation of TMB by H2O2. Combined with colorimetric determination using a UV-Vis spectrophotometer, the quantitative detection of H2O2 and glucose can be achieved. The operation is simple, rapid, low-cost, highly sensitive, and has a low detection limit.

[0031] 3. The Cu-Zn-MOF and Cu-MOF prepared in this invention have a strong bactericidal effect against Staphylococcus aureus and Escherichia coli, with a bactericidal rate of 99% at 80 μg / mL.

[0032] 4. The preparation method provided in this application uses ultrapure water throughout the entire synthesis of metal-MOFs, eliminating the need for organic solvents and making it environmentally friendly. By using a single metal or adjusting the ratio between two metals, the synthesized metal-MOFs exhibit uniform morphology and diverse shapes. With a single metal, they are two-dimensional bipyramidal nanosheets; with a bimetal, they are three-dimensional micron-sized materials. Furthermore, zinc and copper, as trace elements in the human body, play important physiological roles and participate in normal metabolism. By selecting copper salts or combinations of copper and zinc salts, the synthesized metal-MOF materials possess excellent biocompatibility. In addition to exhibiting hydrogen peroxide-like enzyme activity, they also demonstrate strong antibacterial activity against Staphylococcus aureus and Escherichia coli, broadening their application in the field of medical antibacterial technology. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention.

[0034] Figure 1 These are TEM and SEM images of Cu-MOF;

[0035] Figure 2 These are the ultraviolet and infrared spectra of Cu-MOF;

[0036] Figure 3 This is the UV-Vis absorption spectrum of Cu-MOF catalyzing the oxidation of TMB by H2O2;

[0037] Figure 4 The antibacterial effects of different concentrations of Cu-MOF on Staphylococcus aureus and Escherichia coli are shown.

[0038] Figure 5 The images show the UV-Vis spectra of H2O2 at different concentrations in the 400-800 nm wavelength range (a) and the linear relationship between absorbance and H2O2 concentration (b).

[0039] Figure 6 The graph shows the linear relationship between absorbance at 652 nm and glucose concentration (a); and the selectivity for glucose (b).

[0040] Figure 7 These are scanning electron microscope (AC) images and elemental distribution maps (DI) of Cu-Zn-MOF.

[0041] Figure 8 It involves adding Cu in different molar ratios. 2+ and Zn 2+ Scanning electron microscope image of synthesized Cu-Zn-MOF;

[0042] Figure 9 This is the UV-Vis absorption spectrum of TMB oxidized by H2O2 under Cu-Zn-MOF catalysis;

[0043] Figure 10 The antibacterial effects of Cu-Zn-MOF on Staphylococcus aureus and Escherichia coli at different concentrations are shown.

[0044] Figure 11 The images show the UV-Vis spectra of H2O2 at different concentrations in the 400-800 nm wavelength range (a) and the linear relationship between absorbance and H2O2 concentration (b).

[0045] Figure 12 The images show the UV-Vis spectra of glucose at different concentrations in the 400-800 nm wavelength range (a); the linear relationship between absorbance and glucose concentration (b); and the selectivity for glucose (c). Detailed Implementation

[0046] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto.

[0047] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0048] Example 1

[0049] This embodiment provides a bipyramidal Cu-MOF nanozyme, which is made of Cu 2+ A bipyramidal nanostructure formed by self-assembly of 2-methylimidazole with hexadecyltrimethylammonium bromide via coordination bonds.

[0050] Its preparation method is as follows: Preparation method

[0051] Step (1): Dissolve 2-methylimidazole and hexadecyltrimethylammonium bromide in ultrapure water to obtain a 1.32 mol / L 2-methylimidazole solution and a 4 mmol / L hexadecyltrimethylammonium bromide aqueous solution;

[0052] Step (2): Take 10 mL of 1.32 mol / L 2-methylimidazole solution and add it to 15 mL of 4 mmol / L hexadecyltrimethylammonium bromide aqueous solution. Mix the solution by sonication for 10 min. Then add 10 mL of 40 mmol / L copper nitrate solution and sonicate in a water bath for 4 h to obtain the reaction solution.

[0053] Step (3): Centrifuge the reactants obtained in step 2 at 5000 rpm for 10 min and wash them three times with ultrapure water to obtain the biconical Cu-MOF.

[0054] Transmission electron microscopy and scanning electron microscopy of the obtained Cu-MOF are shown in the figure. Figure 1 As shown, Cu-MOF consists of two-dimensional bipyramidal nanosheets with an average length of 300-500 nm and a width of 150-250 nm. See the UV and IR images below. Figure 2 As shown.

[0055] II. Verification of peroxidase activity in Cu-MOF

[0056] The peroxidase activity of Cu-MOF was studied using an H2O2-TMB catalytic oxidation model. 20 μL of TMB (5 mmol / L), 20 μL of H2O2 (500 mmol / L), and 20 μL of Cu-MOF (1 mg / mL) were added to 140 μL of acetate-sodium acetate solution (HAc-NaOAc, pH 5). After standing at room temperature for 30 min, the absorption spectra of the reaction system in the 400-800 nm range were measured using a UV-Vis spectrophotometer. The results are shown below. Figure 3As shown, TMB and TMB+H2O2 have almost no absorption in the 400-800nm ​​range; only when Cu-MOF is added to the TMB+H2O2 system does the system change from colorless to a distinct blue and show a maximum absorption peak at 652nm, indicating that Cu-MOF has peroxidase activity.

[0057] III. Investigation into the Antibacterial Effect of Cu-MOF

[0058] 1. Bacterial Culture: Inoculate the preserved Staphylococcus aureus or Escherichia coli into beef extract peptone liquid medium and incubate at 37°C with shaking for 12-18 hours. Take 1 mL of bacterial suspension, centrifuge at 5000 rpm for 8 minutes, discard the supernatant, resuspend the bacterial cells in 0.9% physiological saline, and then serially dilute the bacterial concentration to 10-1. 6 CFU / mL, for later use.

[0059] 2. Antibacterial effect study: 200 μL of a 10... 6 CFU / mL bacterial suspension was added to 200 μL of Cu-MOF at different concentrations, and treated with shaking at 37℃ for 3 h. 100 μL of the treated bacterial suspension was then spread onto a solid culture medium. Simultaneously, 100 μL of the untreated bacterial suspension was also taken. 6 CFU / mL bacterial suspension was spread onto plates as a control group and incubated at 37℃ for 18-24 hours; the plates were photographed using a fully automated colony counter.

[0060] Antibacterial effect such as Figure 4 As shown, the antibacterial effect increases with increasing material concentration.

[0061] IV. The effect of Cu-MOF catalysis on the oxidation of TMB by H2O2

[0062] 1. Cu-MOF catalyzes the oxidation of TMB by H2O2 to determine H2O2. The operation steps are as follows:

[0063] 70 μL of acetate-sodium acetate buffer solution (pH 5.0), 10 μL of Cu-MOF solution, 10 μL of 5 mM TMB solution, and 10 μL of a series of H2O2 solutions of different concentrations (initial concentrations of 0 mM, 10 mM, 50 mM, 100 mM, 300 mM, 500 mM, and 1000 mM) were sequentially added to a 96-well plate. After reacting at room temperature for 30 min, the reaction system was spectrally scanned using a microplate reader in the wavelength range of 400-800 nm with a step size of 8. At least three parallel experiments were performed for each H2O2 concentration, and the obtained data were plotted and analyzed.

[0064] Based on experimental results, such as Figure 5Findings: The absorbance increases with increasing H2O2 concentration in the range of 0-100 mM; in the range of 0 to 1 mM, the absorbance at 652 nm is linearly related to the H2O2 concentration; and the method has a low detection limit of 0.04283 mM for detecting H2O2.

[0065] 2. Cu-MOF catalyzes the oxidation of TMB by H2O2 to determine glucose. The operation steps are as follows:

[0066] 40 μL of a pH 7.0 acetate-sodium acetate buffer solution, 10 μL of a 1 mg / mL glucose oxidase solution, and 10 μL of glucose solutions of various concentrations (initial concentrations of 0 mM, 6 mM, 10 mM, 14 mM, 20 mM, 26 mM, 30 mM, and 34 mM) were sequentially added to 0.5 mL centrifuge tubes and heated in a 37°C water bath for 30 minutes. After removing the tubes from the water bath, 30 μL of a 5 mM TMB solution, 20 μL of a 5 mg / mL Cu-MOF solution, and 90 μL of a pH 5.0 acetate-sodium acetate buffer solution were added to the above reaction system. The reaction was allowed to proceed for 30 minutes at room temperature. The reaction system was then transferred to a 96-well plate, and the wavelength range of the microplate reader was set to 400-800 nm for spectral scanning. At least three parallel experiments were performed for each glucose concentration, and the obtained data were plotted and analyzed. The experimental results, such as… Figure 6 The study found that the absorbance at 652 nm increased with increasing glucose concentration, showing a linear relationship with glucose concentration; and the method had a low detection limit of 0.269 mM for glucose detection.

[0067] Prepare a 100 mM solution of maltose, galactose, sucrose, and a 20 mM solution of glucose. Determine the selectivity of Cu-MOF for glucose according to the experimental procedures described above. The experimental results, such as... Figure 6 b was found to have excellent selectivity for glucose.

[0068] Example 2

[0069] A bimetallic Cu-Zn-MOF is made from Cu 2+ and Zn 2+ Micron-sized structures formed by self-assembly of 2-methylimidazole with a coordination bond at a molar ratio of 9:1.

[0070] The preparation method of the above Cu-Zn-MOF is as follows:

[0071] Step (1): Dissolve 2-methylimidazole, hexadecyltrimethylammonium bromide, zinc nitrate and copper nitrate in ultrapure water to obtain 1.32 mol / L 2-methylimidazole solution, 4 mmol / L hexadecyltrimethylammonium bromide aqueous solution, and 50 mmol / L zinc nitrate and copper nitrate solutions.

[0072] Step (2): Take 20 mL of 1.32 mol / L 2-methylimidazole solution and add it to 30 mL of 4 mmol / L hexadecyltrimethylammonium bromide aqueous solution. Mix the solution by sonication for 10 min. Then add 18 mL of 50 mmol / L copper nitrate solution and 2 mL of 50 mmol / L zinc nitrate solution. After sonication in a water bath for 5 h, the reaction solution is obtained.

[0073] Step (3): Centrifuge the reactants obtained in step 2 at 3000 rpm for 10 min and wash them three times with ultrapure water to obtain Cu-Zn-MOF.

[0074] The scanning electron microscope and elemental distribution of the obtained Cu-Zn-MOF are shown in the figure. Figure 7 As shown, the bimetallic Cu-Zn-MOF is a supramolecular aggregate formed by the stacking of a large number of small nanoneedles.

[0075] Example 3

[0076] A bimetallic Cu-Zn-MOF is made from Cu 2+ and Zn 2+ Micron-sized structures formed by self-assembly of 2-methylimidazole with a coordination bond at a molar ratio of 1:1.

[0077] The preparation method in this embodiment differs from that in Example 2 in that: in step (2) Cu 2+ and Zn 2+ A molar ratio of 1:1 yields a bimetallic Cu-Zn-MOF, the scanning electron microscope image of which is shown below. Figure 8 As shown in (a).

[0078] Example 4

[0079] A bimetallic Cu-Zn-MOF is made from Cu 2+ and Zn 2+ Micron-sized structures formed by self-assembly of 2-methylimidazole with a coordination bond at a molar ratio of 3:2.

[0080] The preparation method in this embodiment differs from that in Example 2 in that: in step (2) Cu 2+ and Zn 2+ A molar ratio of 3:2 yielded a bimetallic Cu-Zn-MOF, the scanning electron microscope image of which is shown below. Figure 8 As shown in (b).

[0081] Example 5

[0082] A bimetallic Cu-Zn-MOF is made from Cu 2+ and Zn 2+ Micron-sized structures formed by self-assembly of 2-methylimidazole with a coordination bond at a molar ratio of 7:3.

[0083] The preparation method in this embodiment differs from that in Example 2 in that: in step (2) Cu 2+ and Zn 2+ A molar ratio of 7:3 yielded a bimetallic Cu-Zn-MOF, the scanning electron microscope image of which is shown below. Figure 8 As shown in (c).

[0084] The bimetallic Cu-Zn-MOFs used in the following experimental examples were all prepared in Example 2.

[0085] II. Verification of Peroxidase Activity in Cu-Zn-MOF

[0086] The peroxidase activity of Cu-Zn-MOF was studied using a H2O2-TMB catalytic oxidation model. 20 μL of TMB (5 mmol / L), 20 μL of H2O2 (500 mmol / L), and 20 μL of Cu-Zn-MOF (1 mg / mL) were added to 140 μL of acetate-sodium acetate solution (Hac-NaOAc, pH 5). After standing at room temperature for 30 min, the absorption spectra of the reaction system in the 400-800 nm range were measured using a UV-Vis spectrophotometer. The results are as follows: Figure 9 As shown, TMB and TMB+H2O2 have almost no absorption in the 400-800 nm range; only when Cu-Zn-MOF is added to the TMB+H2O2 system does the system change from colorless to a distinct blue and show a maximum absorption peak at 652 nm; indicating that Cu-Zn-MOF has peroxidase activity.

[0087] III. Investigation into the Antibacterial Effect of Cu-Zn-MOF

[0088] 1. Bacterial Culture: Inoculate the preserved Staphylococcus aureus or Escherichia coli into beef extract peptone liquid medium and incubate at 37°C with shaking for 12-18 hours. Take 1 mL of bacterial suspension, centrifuge at 5000 rpm for 8 minutes, discard the supernatant, resuspend the bacterial cells in 0.9% physiological saline, and then serially dilute the bacterial concentration to 10-1. 6 CFU / mL, for later use.

[0089] 2. Antibacterial effect study: 200 μL of a 10... 6CFU / mL bacterial suspension was added to 200 μL of Cu-Zn-MOF at different concentrations, and treated with shaking at 37℃ for 3 h. 100 μL of the treated bacterial suspension was then spread onto a solid culture medium. Simultaneously, 100 μL of the untreated bacterial suspension was also taken. 6 CFU / mL bacterial suspension was spread onto plates as a control group and incubated at 37℃ for 18-24 hours; the plates were photographed using a fully automated colony counter.

[0090] Antibacterial effect such as Figure 10 As shown, the antibacterial effect increases with increasing material concentration.

[0091] IV. The effect of Cu-Zn-MOF catalysis on the oxidation of TMB by H2O2

[0092] 1. Cu-Zn-MOF catalyzes the oxidation of TMB by H2O2 to determine H2O2. The operation steps are as follows:

[0093] 70 μL of acetate-sodium acetate buffer solution (pH 5.0), 10 μL of Cu-MOF solution, 10 μL of 5 mM TMB solution, and 10 μL of a series of H2O2 solutions of different concentrations (initial concentrations of 0 mM, 10 mM, 50 mM, 100 mM, 300 mM, 500 mM, 1000 mM, and 2000 mM) were sequentially added to a 96-well plate. After reacting for 30 min at room temperature, the reaction system was spectrally scanned using a microplate reader in the wavelength range of 400-800 nm with a step size of 8. At least three parallel experiments were performed for each H2O2 concentration, and the obtained data were plotted and analyzed.

[0094] Based on experimental results, such as Figure 11 Findings: The absorbance increases with increasing H2O2 concentration in the range of 0-300 mM; in the range of 0 to 1 mM, the absorbance at 652 nm is linearly related to the H2O2 concentration; and the method has a low detection limit of 0.06996 mM for detecting H2O2.

[0095] 2. Cu-Zn-MOF catalyzes the oxidation of TMB by H2O2 to determine glucose. The operation steps are as follows:

[0096] 40 μL of a pH 7.0 acetate-sodium acetate buffer solution, 10 μL of a 1 mg / mL glucose oxidase solution, and 10 μL of glucose solutions of various concentrations (initial concentrations of 0 mM, 6 mM, 10 mM, 14 mM, 20 mM, 26 mM, 30 mM, and 34 mM) were sequentially added to 0.5 mL centrifuge tubes and heated in a 37°C water bath for 30 minutes. After removing the tubes from the water bath, 30 μL of a 5 mM TMB solution, 20 μL of a 5 mg / mL Cu-MOF solution, and 90 μL of a pH 5.0 acetate-sodium acetate buffer solution were added to the above reaction system. The reaction was allowed to proceed for 30 minutes at room temperature. The reaction system was then transferred to a 96-well plate, and the wavelength range of the microplate reader was set to 400-800 nm for spectral scanning. At least three parallel experiments were performed for each glucose concentration, and the obtained data were plotted and analyzed. The experimental results, such as… Figure 12 a and 6b found that the absorbance at 652 nm increased with increasing glucose concentration, showing a linear relationship with glucose concentration; and the method had a low detection limit of 0.093 mM for glucose detection.

[0097] Prepare a 100 mM solution of maltose, galactose, sucrose, and a 20 mM solution of glucose. Determine the selectivity of Cu-Zn-MOF for glucose according to the experimental procedures described above. The experimental results, such as... Figure 12 c was found to have excellent selectivity for glucose.

Claims

1. A method for preparing a metal-MOF nanozyme, characterized in that, The steps are as follows: Step (1): Dissolve 2-methylimidazole, hexadecyltrimethylammonium bromide, and the metal salt in ultrapure water respectively; Step (2): Add the dissolved 2-methylimidazole solution to the hexadecyltrimethylammonium bromide aqueous solution, sonicate for 5-20 min, add the metal salt solution, and continue sonication in a water bath for 1-5 h to obtain the reaction solution; Step (3): The reactants obtained in step (2) are centrifuged, washed with ultrapure water, and dried to obtain the metal-MOF nanozyme; The metal salt is a combination of copper and zinc salts; The molar ratio of the zinc salt to the copper salt is 1:4 to 1:

20.

2. The method for preparing metal-MOF nanozymes according to claim 1, characterized in that, The copper salt is one or more of copper chloride, copper nitrate, or copper sulfate; the zinc salt solution is one or more of zinc chloride, zinc nitrate, or zinc sulfate.

3. The method for preparing metal-MOF nanozymes according to claim 1, characterized in that, The concentration of the 2-methylimidazole dissolved in ultrapure water is 1-100 mol / L; the concentration of the metal salt dissolved in ultrapure water is 10-300 mmol / L.

4. The method for preparing metal-MOF nanozymes according to claim 1, characterized in that, The ultrasonic power is 60-100 W, and the water bath temperature is 37-80 ℃.

5. The method for preparing metal-MOF nanozymes according to claim 1, characterized in that, The specific process of step (3) is to obtain a precipitate by centrifugation, wash it 3-6 times with ultrapure water, dry it in an oven at a temperature of 50-100℃, and obtain metal-MOF nanozymes by drying.

6. A metal-MOF nanozyme, characterized in that, The metal-MOF nanozyme prepared by any one of the preparation methods described in claims 1-5 is a Cu-Zn-MOF nanozyme.

7. The application of the metal-MOF nanozyme according to claim 6 in the preparation of antibacterial agents against Escherichia coli and Staphylococcus aureus.

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