A biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity and a preparation method and application thereof

Abstract

The application discloses a kind of high CO2 catalytic ability's biomimetic carbonic anhydrase Zn-MOF material and its preparation method and purposes, belong to MOFs material biomimetic enzyme catalysis field.The preparation method is simple in operation, good repeatability, and the obtained biomimetic carbonic anhydrase MOFs material catalytic activity is high, structural stability and good reusability, it is a kind of good biomimetic carbonic anhydrase MOF material, simultaneously the biomimetic carbonic anhydrase Zn-MOF material prepared in the application can be widely applied in biosensor, gas storage, gas separation, CO2 capture conversion, enzyme immobilization and so on field, has higher commercial application value.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of MOFs material biomimetic enzyme catalysis, and particularly relates to a preparation method and application of a biomimetic carbonic anhydrase Zn-MOF material. BACKGROUND

[0002] Carbonic anhydrase (CA) is a zinc-containing metal enzyme widely distributed in organisms, which can reversibly catalyze the hydration reaction of CO2, and maintain the balance of CO2 and HCO3 – in the organism. Through the catalysis of carbonic anhydrase, two neutral molecules of carbon dioxide and water are converted into a weak base (bicarbonate) and H + ion. The hydration efficiency of carbon dioxide can be greatly improved. Carbonic anhydrase can catalyze CO2 in the atmosphere or industrial flue gas to generate HCO3 – , so as to realize the capture and fixation of CO2 and downstream utilization, which has important theoretical research and practical application value under the background of "double carbon" in China.

[0003] However, as a protein, carbonic anhydrase has high biological catalytic activity, but its high cost, complex synthesis process, poor stability, difficulty in storage, difficulty in separation and purification, and poor reusability limit its application in industry.

[0004] The inherent limitations of natural enzymes have promoted the emergence and development of biomimetic enzymes. Biomimetic enzymes are a class of artificial synthetic materials with biological catalytic function. As a new alternative, they have the physicochemical properties of artificial materials and the catalytic function similar to natural enzymes, and have the advantages of stability and catalytic activity. In addition, low cost and simple synthesis conditions make biomimetic enzymes more suitable for large-scale production.

[0005] Metal organic frameworks (MOFs) are a class of organic-inorganic materials connected by metal ions or clusters and organic ligands through coordination bonds. MOFs have extremely high specific surface area, rich pore structure and large pore volume, are easy to synthesize and low in cost, and can be designed and assembled according to the diversity of metal nodes and ligands and the diversity of connection modes, so as to have rich structures and functions and have extremely broad application prospects. The structure of MOFs can be regulated, and according to the known catalytic mechanism of enzymes, the metal center and ligand of MOFs can be specifically assembled to have a catalytic active center similar to natural enzymes. At the same time, due to the key role of organic ligands in enzyme catalytic reaction, modification or replacement of organic ligands in MOFs becomes a new idea to improve their performance.

[0006] ZIFs series of materials have a structure similar to inorganic zeolite materials, and the topological structure is consistent with many silicon-aluminum molecular sieves, and has the advantages of structural stability, large specific surface area, high temperature resistance, acid and alkali resistance, organic solvent resistance and the like. ZIF-8 is one of the ZIFs materials, and its structural unit is composed of divalent metal zinc ions and four 2-methyl imidazole ligands. Similar to the catalytic active center of natural carbonic anhydrase, it has the advantages of simple synthesis process, structural stability and the like, and has been widely used in the research of catalyzing CO2 hydration reaction.

[0007] Although the ZIF-8 biomimetic enzyme has stability and reusability that cannot be compared with natural enzymes, its catalytic activity still has a certain gap compared with natural carbonic anhydrase, so improving the activity of the ZIF-8 biomimetic enzyme is still a problem to be solved at present.

[0008] In order to improve the catalytic activity of the above-mentioned biomimetic enzyme, on the basis of the ZIF-8 biomimetic carbonic anhydrase, Zn-MOF material is synthesized by one-pot method with zinc ions and 2-amino imidazole as raw materials, while retaining the catalytic active center, introducing Lewis basic site amino, improving the CO2 adsorption capacity of the material, and the synergistic catalysis of the two exhibits higher catalytic activity. At the same time, vortex oscillation dispersion synthesis is adopted in the synthesis process, and the prepared Zn-MOF material has good dispersity. SUMMARY

[0009] The application provides a kind of biomimetic carbonic anhydrase Zn-MOF material and its preparation method and purpose. The method is low in cost, simple in operation and good in repeatability, and the obtained biomimetic carbonic anhydrase MOFs material has high catalytic activity, good structural stability and good reusability, and is a good biomimetic carbonic anhydrase MOF material, which can be widely applied in the fields of biosensor, gas storage, gas separation, CO2 capture and conversion, enzyme immobilization, etc.

[0010] The first object of the application is to provide a method for preparing biomimetic carbonic anhydrase Zn-MOF material, the steps are as follows:

[0011] (1) 0-30 mL of methanol is added to 15 mL of zinc acetate solution, and a vortex mixer is used to vortex for 30 s to ensure uniform mixing of the solution, to obtain a methanol-zinc acetate mixed solution.

[0012] In the step (1), the amount of methanol added affects the yield of Zn-MOF material and the uniformity of the crystal, and in the present application, the addition of 15 mL of methanol can obtain spherical Zn-MOF crystal with good uniformity, and under the premise of not affecting the crystal morphology, the yield of biomimetic carbonic anhydrase Zn-MOF is increased as much as possible.

[0013] In the step (1), the methanol-zinc acetate mixed solution contains zinc acetate with a final concentration of 0.1 M.

[0014] (2) adding a 2-aminoimidazole solution with a concentration of 1M into the mixed solution obtained in step (1), and vortexing for 30s using a vortex mixer to ensure that the solution is uniformly mixed, to obtain a 2-aminoimidazole-methanol-zinc acetate mixed solution;

[0015] In the step (2), the application simulates the catalytic active center of carbonic anhydrase by coordination of zinc ions and 2-aminoimidazole, and the addition ratio of the two can affect the yield of the biomimetic carbonic anhydrase Zn-MOF.

[0016] In the step (2), a 2-aminoimidazole-methanol-zinc acetate mixed solution is obtained, and the final concentration of 2-aminoimidazole is 0.5M.

[0017] (3) placing the 2-aminoimidazole-methanol-zinc acetate mixed solution in a dark place at 25℃ for 5-30h;

[0018] (4) (5) centrifuging the mixed solution obtained in step (3), washing the obtained precipitate with water for three times, and vacuum freeze-drying for 48h to finally obtain the biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity.

[0019] In the step (4) (5), the centrifugal speed is 10000-12000rpm, and the centrifugal time is 10-60min.

[0020] In an embodiment of the application, the volume of methanol in the step (1) can be 0, 5, 10, 15, 20, 25, or 30mL.

[0021] Preferably, the addition amount of methanol is 10-20mL, and more preferably 15mL.

[0022] In an embodiment of the application, the incubation time of the 2-aminoimidazole-methanol-zinc acetate mixed solution in the step (3) can be 5, 10, 15, 20, 25, or 30h.

[0023] Preferably, the growth time of the 2-aminoimidazole-methanol-zinc acetate in the step (3) is 20-25h, and under this condition, the yield and crystallinity of the biomimetic carbonic anhydrase Zn-MOF are better.

[0024] In an embodiment of the application, in the step (4), the centrifugal speed can be 10000, 11000, or 12000rpm, and the centrifugal time can be 10, 20, 30, 40, 50, or 60min.

[0025] Preferably, in the step (4), the centrifugal speed is 10000-12000rpm, and the centrifugal time is 40min.

[0026] Preferably, in the step (5), the washing step is the same volume of ultrapure water shaking / vortexing cleaning.

[0027] Preferably, the method for preparing the biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity, the steps are as follows:

[0028] (a) 15 mL of methanol is added to a 0.2 M zinc acetate solution, and a vortex mixer is used to vortex for 30 s to ensure that the solution is uniformly mixed, to obtain a methanol-zinc acetate mixed solution, wherein the final concentration of zinc acetate in the zinc acetate-methanol mixed solution is 0.1 M;

[0029] (b) A 1 M 2-aminoimidazole solution is added to the mixed solution obtained in step (a), and a vortex mixer is used to vortex for 30 s to ensure that the solution is uniformly mixed, to obtain a 2-aminoimidazole-methanol-zinc acetate solution with a final concentration of 0.5 M 2-aminoimidazole;

[0030] (c) The 2-aminoimidazole-methanol-zinc acetate solution is incubated in the dark at 25℃ for 20-25 h;

[0031] (d) The mixed solution obtained in step (c) is centrifuged at a speed of 10,000-12,000 rpm for 40 min;

[0032] (e) The precipitate obtained in step (d) is washed with water three times, and vacuum freeze-dried for 48 h to obtain the biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity;

[0033] Preferably, in the step (e), the washing step is the same volume of ultrapure water shaking / vortexing cleaning.

[0034] The second object of the present application is to provide the biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity prepared by the above method, which has the advantages of good structural stability, high catalytic activity, good reusability, etc.

[0035] The third object of the present application is that the biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity can be widely used in the fields of biosensors, gas storage, gas separation, CO2 capture and conversion, enzyme immobilization, etc.

[0036] Compared with the existing technology, the present application has the following advantages:

[0037] 1. The application utilizes the coordination of metal ion zinc ion and 2-aminoimidazole to simulate the catalytic active center of natural carbonic anhydrase. Compared with natural enzymes, the Zn-MOF biomimetic enzyme has both the physical and chemical properties of artificial materials and the catalytic function similar to natural enzymes, and has the advantages of stability and catalytic activity. Its structure is spherical porous structure, which has larger specific surface area and higher catalytic activity without affecting the mass transfer of the substrate.

[0038] 2. The application first proposes the use of 2-aminoimidazole to introduce amino functional groups with high CO2 adsorption capacity before synthesis. While retaining the catalytic active center, the introduction of Lewis base site amino improves the CO2 adsorption capacity of the material, and the synergistic catalysis of the two exhibits higher catalytic activity. At the same time, vortex oscillation dispersion synthesis is adopted in the synthesis process, and the prepared Zn-MOF material has good dispersity.

[0039] The 2-aminoimidazole and zinc acetate solution used in the application are mixed in a certain proportion, and under the regulation of methanol solution, the biomimetic carbonic anhydrase Zn-MOF material with good crystallinity is synthesized by vortex oscillation dispersion. It has the characteristics of low cost, simple synthesis, high catalytic activity, stable structure and good reusability, and is a good biomimetic carbonic anhydrase MOF material. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The scanning electron microscope SEM microstructure of the biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity synthesized under the optimal conditions of the application;

[0041] Figure 2 The X-ray diffraction (XRD) spectrum of the biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity synthesized under the optimal conditions of the application;

[0042] Figure 3 The infrared spectrum (FTIR) spectrum of the biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity synthesized under the optimal conditions of the application;

[0043] Figure 4 Comparison of enzyme catalytic activity of the biomimetic carbonic anhydrase Zn-MOF material prepared under optimal conditions at different reaction temperatures;

[0044] Figure 5 Comparison of enzyme catalytic activity of the biomimetic carbonic anhydrase Zn-MOF material prepared under optimal conditions at different pH reaction conditions;

[0045] Figure 6 Comparison of temperature tolerance of the biomimetic carbonic anhydrase ZIF-8 and the biomimetic carbonic anhydrase Zn-MOF material prepared under optimal conditions;

[0046] Figure 7 Comparison of pH tolerance of biomimetic carbonic anhydrase ZIF-8 and Zn-MOF prepared under optimal conditions;

[0047] Figure 8 Comparison of reusability of biomimetic carbonic anhydrase ZIF-8 and Zn-MOF prepared under optimal conditions;

[0048] Figure 9 Comparison of enzyme catalytic activity of biomimetic carbonic anhydrase ZIF-8 and Zn-MOF prepared under optimal conditions;

[0049] Figure 10 Comparison of enzyme catalytic activity of biomimetic carbonic anhydrase ZIF-8, Zn-MOF and natural carbonic anhydrase;

[0050] Figure 11 Qualitative comparison of CO2 hydration performance of carbonic anhydrase, biomimetic carbonic anhydrase ZIF-8 and Zn-MOF prepared under optimal conditions; DETAILED DESCRIPTION

[0051] The present application will be described in detail below with specific embodiments. Unless otherwise specified, the technical means used in the present application are methods well known to those skilled in the art. In addition, the embodiments should be understood as illustrative, rather than limiting the scope of the present application, the essence and scope of the present application are limited only by the claims. For those skilled in the art, various changes or modifications to the material composition and amount in these embodiments without departing from the essence and scope of the present application also belong to the protection scope of the present application. The present application will be further described below in conjunction with specific examples.

[0052] Example 1 Synthesis of biomimetic carbonic anhydrase Zn-MOF material under the condition of adding different volumes of methanol and relative enzyme catalytic activity.

[0053] Synthesis of biomimetic carbonic anhydrase Zn-MOF material according to the following steps

[0054] Accurately weigh 0.5505 g of zinc acetate and 2.493 g of 2-aminoimidazole, respectively, and add 15 and 30 mL of ultrapure water to dissolve them completely to obtain zinc acetate solution and 2-aminoimidazole solution, respectively. Accurately weigh 0, 5, 10, 15, 20, 25, and 30 mL of methanol solution and add them to the zinc acetate solution, shake and mix to obtain a methanol-zinc acetate mixed solution with a zinc acetate concentration of 0.1 M. Add the 2-aminoimidazole solution to the methanol-zinc acetate mixed solution to obtain a 2-aminoimidazole-methanol-zinc acetate mixed solution, in which the final concentration of 2-aminoimidazole is 0.5 M and the final concentration of zinc acetate is 50 mM. Place the obtained mixed solution in a dark place at 25°C for 20-25 h. Then centrifuge at 10,000-12,000 rpm for 40 min, wash the precipitate with an equal volume of ultrapure water for 3 times, and vacuum freeze-dry to obtain the Zn-MOF biomimetic carbonic anhydrase material with high CO2 catalytic activity.

[0055] The enzyme catalytic activity determination method is as follows: add 600 μL of Tris-HCl buffer (50 mM, pH = 8), 200 μL of Zn-MOF suspension (0.1 mg / mL), and 200 μL of substrate p-NPA (3 mM) solution into a 1.5 mL centrifuge tube. Measure the change in absorbance of the reaction solution at a wavelength of 420 nm at room temperature, and calculate the esterase activity by a standard curve.

[0056] The relative enzyme catalytic activity is calculated as follows:

[0057] Relative enzyme activity = enzyme activity under different experimental conditions / enzyme activity under the best reaction conditions in all experiments x 100%

[0058] The experimental results are as follows: under the synthesis conditions of 0, 5, 10, 15, 20, 25, and 30 mL of methanol, the relative enzyme activities of the biomimetic carbonic anhydrase Zn-MOF material are 63.41%, 74.32%, 87.46%, 98.67%, 100%, 96.77%, and 93.45%, respectively. When the volume of methanol is too high, although the enzyme catalytic activity of the prepared biomimetic carbonic anhydrase Zn-MOF is high, with the increase of the volume of methanol, the difficulty of sample centrifugation increases and the yield is low.

[0059] The relative enzyme activities of the biomimetic carbonic anhydrase Zn-MOF material prepared under the best reaction conditions of Example 2 under different temperatures.

[0060] The Zn-MOF biomimetic enzyme is synthesized as follows:

[0061] Zinc acetate 0.5505 g and 2-aminoimidazole 2.493 g were accurately weighed and dissolved in 15 mL and 30 mL of ultrapure water respectively to obtain zinc acetate solution and 2-aminoimidazole solution with concentrations of 0.2 M and 1 M. 15 mL of methanol solution was accurately weighed and added to the zinc acetate solution, and after shaking and mixing, a methanol-zinc acetate mixed solution with a zinc acetate concentration of 0.1 M was obtained. The 2-aminoimidazole solution was added to the methanol-zinc acetate mixed solution to obtain a 2-aminoimidazole-methanol-zinc acetate mixed solution, and at this time the final concentration of 2-aminoimidazole was 0.5 M and the final concentration of zinc acetate was 50 mM. The resulting mixed solution was placed in the dark at 25°C for 20-25 h. Then centrifugation was performed at 10,000-12,000 rpm for 40 min, and the precipitate was washed with an equal volume of ultrapure water for 3 times and then vacuum freeze-dried to obtain the biomimetic carbonic anhydrase Zn-MOF material.

[0062] The enzyme catalytic activity determination method was as follows: 600 μL of Tris-HCl buffer (50 mM, pH = 8), 200 μL of Zn-MOF suspension (0.1 mg / mL), and 200 μL of substrate p-NPA (3 mM) solution were added to a 1.5 mL centrifuge tube. The mixed system was placed at 15, 25, 35, 45, 55, 60, 70, and 80°C for 3 min, and the change in absorbance of the reaction solution at a wavelength of 420 nm was measured. The esterase activity was calculated by a standard curve.

[0063] The enzyme catalytic activity determination results are shown in Table 1. Figure 4 At a reaction temperature of 15, 25, 35, 45, 55, 60, 70, and 80°C, the relative enzyme activity of Zn-MOF was 44.1%, 55.2%, 57.6%, 67.1%, 83.8%, 87.3%, 100%, and 88.6% respectively. The catalytic activity of the biomimetic carbonic anhydrase Zn-MOF increased with increasing temperature, and the optimal reaction temperature was 70°C.

[0064] The relative enzyme activity of the biomimetic carbonic anhydrase Zn-MOF material prepared under the optimal reaction conditions of Example 3 under different pH reaction conditions.

[0065] Accurately take 0.5505 g of zinc acetate, 2.493 g of 2-aminoimidazole, and 15 mL and 30 mL of ultrapure water respectively to make them fully dissolved to obtain zinc acetate solution and 2-aminoimidazole solution with concentrations of 0.2 M and 1 M. Accurately take 15 mL of methanol solution into the zinc acetate solution, shake and mix to obtain a methanol-zinc acetate mixed solution with a zinc acetate concentration of 0.1 M, and then add the 2-aminoimidazole solution into the methanol-zinc acetate mixed solution to obtain a 2-aminoimidazole-methanol-zinc acetate mixed solution, in which the final concentration of 2-aminoimidazole is 0.5 M and the final concentration of zinc acetate is 50 mM. Place the obtained mixed solution in a dark place at 25℃ for 20-25 h. Then centrifuge at 10000-12000 rpm for 40 min, wash the precipitate with an equal volume of ultrapure water for 3 times, and then freeze-dry under vacuum to obtain the biomimetic carbonic anhydrase Zn-MOF material.

[0066] The enzyme catalytic activity determination method is to add 600 μl of Tris-HCl buffer (50 mM) with pH of 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 200 μL of Zn-MOF suspension (0.1 mg / mL), and 200 μL of substrate p-NPA (3 mM) solution into a 1.5 mL centrifuge tube. After reaction at room temperature for 3 min, the change of absorbance of the reaction solution at a wavelength of 420 nm is determined, and the esterase activity is calculated by a standard curve.

[0067] The enzyme catalytic activity determination results are shown in the following table: Figure 5 Under the conditions of pH of 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, the relative enzyme activities of Zn-MOF are 3.4%, 7.5%, 10.4%, 16.7%, 62.7%, 83.6%, 100%, 65.7%, 53.7%, and 20.9% respectively. Since the acidic condition can destroy the structure of the biomimetic carbonic anhydrase Zn-MOF and inhibit the esterase reaction, the enzyme catalytic activity is low under the acidic condition.

[0068] (I) Temperature tolerance comparison

[0069] Experimental method: 0.1 mg / mL of ZIF-8 and Zn-MOF were respectively placed in a 80℃ water bath, and after constant temperature water bath for 0, 2, 4, 6, 8, 10, 12 h, 1 mL of biomimetic carbonic anhydrase ZIF-8 and Zn-MOF suspension was taken out, cooled at room temperature, and then the experiment was carried out, and the reaction system without adding biomimetic carbonic anhydrase sample was used as a blank control.

[0070] Enzyme catalytic activity determination method: the enzyme catalytic activity determination method and the relative enzyme activity calculation are the same as in Example 1

[0071] The enzyme catalytic activity determination results are shown in the following table:Figure 6 The enzyme catalytic activity determination was performed after heat treatment at 80℃ for 2, 4, 6, 8, 10, 12h. The enzyme catalytic activity of the biomimetic carbonic anhydrase ZIF-8 and Zn-MOF showed an upward trend within 12h and tended to be stable finally. The reason was that some solvent small molecules and excess imidazole also participated in the coordination of the outer surface metal center during the preparation of ZIF-8 and Zn-MOF. Under high temperature and other severe conditions, the coordination bond was most likely to break, forming active centers with catalytic ability, thereby showing an increase in esterase activity. After a period of hydrothermal treatment, the active sites on the surface of ZIF-8 and Zn-MOF particles were close to saturation, and the esterase activity tended to be stable.

[0072] (Three) Reusability comparison

[0073] Experimental method: 0.1mg / mL of ZIF-8 and Zn-MOF were respectively placed in Tris-HCl buffer (50mM) with pH of 7.5, 8.5, 9.5, 10.5, 11.5, and room temperature was kept for 24h. The reaction system without biomimetic carbonic anhydrase sample was used as blank control.

[0074] Enzyme catalytic activity determination method: the enzyme catalytic activity determination method and relative enzyme activity calculation were the same as in Example 1

[0075] Enzyme catalytic activity determination results refer to the appendix Figure 7 After 24h of treatment in Tris-HCl buffer (50mM) with pH of 7.5, 8.5, 9.5, 10.5, 11.5, the enzyme activity residual rate of biomimetic carbonic anhydrase Zn-MOF was higher than that of ZIF-8 at each gradient pH, and the activity loss of both was larger at lower pH.

[0076] (Three) Reusability comparison

[0077] Experimental method: 6mL of Tris-HCl buffer (50mM, pH=8), 2mL of substrate p-NPA (3mM), and 2mL of ZIF-8 or Zn-MOF suspension (0.5mg / mL) were added to a 20mL centrifuge tube. 0.2mL of the reaction solution was taken to determine the change in absorbance at a wavelength of 420nm. The remaining reaction solution was centrifuged at 10000rpm for 3min, and the precipitate was washed with water. 7.2mL of Tris-HCl buffer (50mM, pH=8) and 1.8mL of substrate p-NPA (3mM) were added, and the above operation was repeated. The reaction system without biomimetic carbonic anhydrase sample was used as blank control.

[0078] Enzyme catalytic activity determination method: the enzyme catalytic activity determination method and relative enzyme activity calculation were the same as in Example 1

[0079] Enzyme catalytic activity determination results refer to the appendixFigure 8 The recycling of biomimetic carbonic anhydrase ZIF-8 and Zn-MOF was carried out, and the activity of the first reaction was taken as 100%. The experimental results showed that the biomimetic carbonic anhydrase Zn-MOF had good reusability. With the increase of the number of uses, the enzyme catalytic activity gradually decreased. After being reused for 6 times, the biomimetic carbonic anhydrase ZIF-8 and Zn-MOF retained 68% and 65% of the initial enzyme activity, respectively. From the enzyme activity value, the activity of Zn-MOF was about 2 times that of ZIF-8. The activity of Zn-MOF decreased faster, and the reason was that the spherical structure had a larger specific surface area, which led to faster loss of active sites.

[0080] (iv) Comparison of esterase activity of biomimetic carbonic anhydrase ZIF-8 and Zn-MOF

[0081] Experimental method: 50 mM Tris-HCl buffer was prepared, the pH was adjusted to 9.5, and the mass concentration of biomimetic carbonic anhydrase ZIF-8 and Zn-MOF suspension was 0.1, 0.5, 1 mg / mL respectively. 600 μL of Tris-HCl buffer, 200 μL of ZIF-8 or Zn-MOF suspension, and 200 μL of substrate p-NPA (3 mM) solution were added to a 1.5 mL centrifuge tube. The reaction system without adding biomimetic carbonic anhydrase sample was used as a blank control group.

[0082] Enzyme catalytic activity determination method: the enzyme catalytic activity determination method and the relative enzyme activity calculation were the same as in Example 1

[0083] The experimental results are shown in the accompanying Figure 9 Compared with the blank, the biomimetic carbonic anhydrase ZIF-8 and Zn-MOF had certain esterase activity. Compared with ZIF-8, the enzyme catalytic activity of biomimetic carbonic anhydrase Zn-MOF increased by about 10 times under the same mass concentration. This was because the organic ligand 2-aminoimidazole in Zn-MOF acted as a Lewis base site, which had higher adsorption capacity for CO2 than the organic ligand 2-methylimidazole in ZIF-8.

[0084] (v) Comparison of esterase activity of biomimetic carbonic anhydrase ZIF-8 and Zn-MOF with natural carbonic anhydrase

[0085] Experimental method: 50 mM Tris-HCl buffer was prepared, the pH was adjusted to 8.5, and the mass concentration of biomimetic carbonic anhydrase ZIF-8, Zn-MOF, and natural carbonic anhydrase suspension was 1 mg / mL. 600 μL of Tris-HCl buffer, 200 μL of enzyme suspension, and 200 μL of substrate p-NPA (3 mM) solution were added to a 1.5 mL centrifuge tube. The reaction system without adding biomimetic carbonic anhydrase sample was used as a blank control group.

[0086] Enzyme catalytic activity determination method: enzyme catalytic activity determination method and relative enzyme activity calculation are the same as example 1

[0087] Enzyme catalytic activity determination results refer to the attached Figure 10 Under the same mass concentration, the enzyme catalytic activity of the biomimetic carbonic anhydrase ZIF-8 and Zn-MOF is 1.6 and 4.8 times that of the natural carbonic anhydrase, respectively.

[0088] (VI) Comparison of the CO2 hydration performance of biomimetic carbonic anhydrase ZIF-8 and Zn-MOF

[0089] The experimental method is to prepare a 0.1M Na2CO3 solution, adjust the pH to 11.3. Accurately weigh 20mg of ZIF-8, Zn-MOF sample into 20mL Na2CO3 solution, ultrasonic for 3min to make the sample evenly dispersed, put the pH meter probe into the solution, and blow CO2 gas with a flow rate of 20mL / min, the CO2 hydration reaction of biomimetic carbonic anhydrase generates HCO3 – , thereby causing the pH to drop, and the change of pH with time is recorded, and the reaction system without adding biomimetic enzyme sample is used as a blank control group.

[0090] Determination results refer to the attached Figure 11 Compared with the blank, the pH of the Na2CO3 solution decreases faster after adding the biomimetic carbonic anhydrase ZIF-8 and Zn-MOF, both of which have a certain catalytic ability for CO2 hydration. Under the same mass concentration, the catalytic ability of Zn-MOF is stronger than that of ZIF-8, and the reason is that the catalytic active center in Zn-MOF and the amino functional group with high CO2 adsorption capacity synergistically catalyze, which enhances the catalytic ability of CO2 hydration reaction.

[0091] The above examples only express several embodiments of the present application, which are described in more detail and in detail, but the technical scope is not limited to the above embodiments. For those skilled in the art, various improvements and implementations can be made without departing from the concept of the present application, which are all within the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. Use of a biomimetic carbonic anhydrase Zn-MOF material in the hydration of CO2, characterized in that, The biomimetic carbonic anhydrase Zn-MOF material is synthesized from zinc ions and an organic ligand 2-aminoimidazole, and is prepared by vortex shaking dispersion. The Zn-MOF material has a spherical structure, has a catalytic active center similar to that of natural carbonic anhydrase, and can synergistically catalyze the amino functional group with high CO2 adsorption capacity, thereby having excellent carbonic anhydrase catalytic activity and good enzyme activity recovery rate, and good stability, easy recycling and reuse. The specific synthesis process comprises the following steps: (1) 0-30 mL of methanol is added to a zinc acetate solution, and a vortex mixer is used to vortex for 30 s to ensure uniform mixing of the solution, to obtain a methanol-zinc acetate solution, and the final concentration of zinc acetate is 0.1 M; (2) 2-aminoimidazole solution is added to the mixed solution obtained in step (1), and a vortex mixer is used to vortex for 30 s to ensure uniform mixing of the solution, to obtain a 2-aminoimidazole-methanol-zinc acetate solution, and the final concentration of 2-aminoimidazole is 0.5 M; (3) The mixed solution obtained in step (2) is placed in the dark and at 25℃ for 5-30 h; (4) The mixed solution obtained in step (3) is centrifuged at a speed of 10,000-12,000 rpm for 10-60 min; (5) The precipitate obtained in step (4) is washed with water three times, vacuum freeze-dried for 48 h, and a biomimetic carbonic anhydrase Zn-MOF material with high CO2 catalytic capacity is obtained.

2. Use of a biomimetic carbonic anhydrase Zn-MOF material according to claim 1 for CO2 hydration, characterized in that, In step (3), the incubation time of the obtained solution is 5-30 h.

3. Use of a biomimetic carbonic anhydrase Zn-MOF material according to claim 1 in CO2 hydration, characterized in that, Compared with the biomimetic carbonic anhydrase ZIF-8, the esterase activity of the Zn-MOF material is increased by 10 times.

Images