A chiral manganese dioxide nanozyme with high laccase activity and high selectivity, and a preparation method and application thereof

Abstract

The application belongs to the field of material chemistry, and particularly relates to a chiral manganese dioxide nanomzyme with high laccase activity and high selectivity, and a preparation method and application thereof. The application mainly comprises the following aspects: synthesis of the chiral manganese dioxide nanomzyme and optimization of the synthesis conditions, a 2,4-dichlorophenol (2,4-DP) degradation method: using the laccase-mimicking property of the chiral manganese dioxide nanomzyme to catalyze 2,4-dichlorophenol, and selective catalysis of chiral substrates: using the selective catalysis of the chiral manganese dioxide nanomzyme on chiral substrates L-DOPA and D-DOPA. The application provides a synthesis method of a biomimetic laccase with a catalytic efficiency 20 times higher than that of natural laccase and a chiral manganese dioxide nanomzyme with selective catalysis, and the biomimetic laccase and the chiral manganese dioxide nanomzyme have good application prospects.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of material chemistry, and particularly relates to a chiral manganese dioxide nanoscale enzyme with high laccase activity and high selectivity, and a preparation method and application thereof. BACKGROUND

[0002] Phenolic pollutants such as 2,4-dichlorophenol have significant harm to the environment, and are highly toxic and difficult to degrade organic pollutants, and are widely distributed in the natural environment. 2,4-dichlorophenol is toxic to aquatic organisms, has a negative impact on the aquatic ecosystem, and is difficult to be degraded by microorganisms in the natural environment, and will exist in the environment for a long time, causing persistent pollution to the environment. Researchers have found that laccase can degrade 2,4-dichlorophenol, but the stability of natural laccase is poor and the cost is high, which is not suitable for large-scale application in industry. The specificity of natural laccase to substrates is small, and it can only catalyze the degradation of certain specific organic substances, which limits its application range.

[0003] A core challenge of asymmetric catalysis is how to design and synthesize catalysts with high selectivity in order to efficiently catalyze certain reactions so that the products have a clear chiral structure. Chiral manganese compounds have potential application value in asymmetric catalysis because manganese is a transition metal with rich chemical reactivity and can participate in various reactions such as oxidation, nucleophilic reaction, addition reaction, etc. Chiral manganese compounds not only can enhance the selectivity of catalytic reaction, but also can provide efficient control of chiral center, so as to realize the synthesis of high-yield chiral products. SUMMARY

[0004] In order to solve the above-mentioned technical problems, the application provides the following technical solutions:

[0005] The application prepares a new type of laccase-like active nanoscale enzyme to catalyze the degradation of phenolic pollutants, and uses amino acids as chiral ligands to prepare a chiral manganese dioxide nanoscale enzyme for efficient degradation of 2,4-DP and catalytic conversion of chiral substrates. The nanoscale enzyme has higher catalytic efficiency than natural laccase and obvious selectivity to L / D-DOPA.

[0006] The application provides a preparation method of a chiral manganese dioxide nanoscale enzyme with high laccase activity and high selectivity, comprising the following steps:

[0007] S11: dissolving manganese sulfate and potassium permanganate in water, and then adding part of amino acids to obtain a salt solution;

[0008] S12: adding a base to the salt solution to form an emulsion;

[0009] S13: re-adding the remaining amino acid and ethanol to the emulsion, heating the reaction at 48-52℃ for 40-50min to obtain a reaction solution; the amino acid in the step S11 and the step S13 is the same;

[0010] S14: post-treating the reaction solution to obtain the manganese dioxide nanoscale enzyme.

[0011] Preferably, the molar ratio of the amino acid in the step S11 and the step S13 is 1:2.

[0012] Preferably, the amino acid is selected from glutamic acid (Glu), histidine (His), tyrosine (Ary), phenylalanine (Phe), cysteine (Cys) or tryptophan (Tar).

[0013] Preferably, the amino acid is a left-handed amino acid or a right-handed amino acid.

[0014] Preferably, in the step S11, the mass ratio of manganese sulfate and potassium permanganate is 0.15-0.2:0.35-0.4.

[0015] Preferably, the mixing method is stirring.

[0016] Preferably, the base is selected from potassium hydroxide.

[0017] Preferably, the amino acid is an aqueous solution of amino acid, and the concentration is 0.1M.

[0018] Preferably, in the step S14, the post-treatment method is cooling to room temperature, solid-liquid separation and drying.

[0019] Further, the drying temperature is 60℃.

[0020] Further, the solid-liquid separation method is centrifugal collection of precipitate.

[0021] Specifically, the centrifugal speed is 4000rpm, the time is 2min, and the number of times is 5.

[0022] The application also provides a chiral manganese dioxide nanoscale enzyme with high laccase activity and high selectivity prepared by the above preparation method.

[0023] The application also provides the application of the chiral manganese dioxide nanoscale enzyme with high laccase activity and high selectivity in catalytic degradation of 2,4-dichlorophenol (2,4-DP).

[0024] Process of catalytic reaction: first, 1 mg / mL chiral MnO2 nanoscale enzyme solution was reacted with 2,4-DP (1 mg / mL) and 4-AP (1 mg / mL) in Tri-HCl (30 mM pH 6.8) buffer solution. Subsequently, the above reaction solution was centrifuged, and the supernatant was collected to measure the absorbance at λ = 510 nm.

[0025] Catalytic reaction principle: in the presence of oxygen, laccase catalyzes the oxidation of polychlorophenols, and chlorophenol is oxidized into free radicals or reactive quinones, etc., which then undergo mutual coupling to form polymers, thereby reducing the toxicity of these toxic substances by reducing their solubility. This reaction mechanism includes the transfer of electrons and protons on the phenol to form free radicals, 1 electron from the substrate is transferred to oxygen via laccase, 2 free radicals are randomly combined to form dimers during oxidation, and the dimers are isomerized into stable aromatic ring products. In addition, dimers can also form free radicals, which can form trimers and even polymers through a similar pathway to generate dimers.

[0026] Preferably, the application of catalytic degradation of 2,4-dichlorophenol (2,4-DP) comprises the following steps:

[0027] S21: 4-aminobenzoic acid (4-AP), 2,4-dichlorophenol (2,4-DP) is dissolved in Tri-HCl buffer to obtain a mixture;

[0028] S22: Add the above MnO2 nanoscale enzyme to the mixture, centrifuge after reaction at room temperature, and measure the absorbance of the supernatant at 510 nm.

[0029] The application also provides the application of the above high laccase activity and high selectivity chiral MnO2 nanoscale enzyme in selective catalysis of L / D-dopa (L / D-DOPA).

[0030] Process of catalytic reaction: first, 100 μL L / D-DOPA (1 mg / mL) is added to 800 μL Tri-HCl (30 mM pH 6.8) buffer solution, and then 100 μL chiral nanoscale enzyme solution (1 mg / mL) is added. After a period of reaction, the above reaction solution is centrifuged, and the supernatant is collected to measure the absorbance at λ = 475 nm.

[0031] Catalytic reaction principle: the process of chiral MnO2 nanoparticle catalytic oxidation of L / D-DOPA depends on the stereomatching effect of its helical structure and the substrate. The catalytic process is divided into three stages: catechol is oxidized to semiquinone radical by single electron, Mn 4+ Redox pair drives the formation of dopaquinone, and finally polymerizes into helically arranged melanin.

[0032] Preferably, the application in catalyzing the degradation of 2,4-dichlorophenol (2,4-DP) comprises the following steps:

[0033] S31: adding L / D-dopa into Tri-HCl buffer solution to obtain a mixed solution;

[0034] S32: adding the above high-laccase-activity and high-selectivity chiral manganese dioxide nanoscale enzyme into the mixed solution, centrifuging after reaction at room temperature, and measuring the absorbance of the supernatant at 475 nm.

[0035] The technical scheme of the present application has the following advantages compared with the prior art:

[0036] The present application has prepared chiral manganese dioxide nanoscale enzyme with uniform structure, which has good degradation efficiency of phenolic pollutants compared with natural laccase. According to enzyme kinetics experiments, the maximum reaction rate of the nanoscale enzyme synthesized by one kind of amino acid as a ligand is as high as 0.048±0.002mM·min -1 In addition, the chiral nanoscale enzyme also has the ability to selectively catalyze chiral substrates. L-Phe-MnO2 in the present application shows strong selectivity for L-DOPA, while D-Phe-MnO2 shows strong selectivity for D-DOPA. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 are example effect pictures; wherein a is an example effect picture of the present application catalyzing 2,4-dichlorophenol, and b is an example effect picture of the present application catalyzing DOPA.

[0038] Figure 2 are pictures of characterization of samples of the present application; wherein a is a scanning electron microscope (SEM) picture of the present application preparing chiral manganese dioxide nanoparticles D-MnO2, b is a scanning electron microscope (SEM) picture of the present application preparing chiral manganese dioxide nanoparticles L-MnO2, c is a Fourier infrared spectrum characterization picture of the present application preparing D / L-MnO2, d is an X-ray diffraction (XRD) characterization picture of the present application preparing D / L-MnO2, e is an X-ray photoelectron spectroscopy (XPS) characterization picture of the present application preparing D / L-MnO2, and f is a circular dichroism spectrum characterization picture of the present application preparing D / L-MnO2.

[0039] Figure 3Catalytic ability diagram and UV absorption spectrum; wherein a is the ability diagram of the chiral enzyme synthesized by different ligands in the enzyme kinetics experiment of the application for catalytically degrading 2,4-DP and L / D-DOPA, b is the UV absorption spectrum of D-Phe-MnO2 catalytically degrading 2,4-DP in the enzyme kinetics experiment of the application for catalytically degrading 2,4-DP and L / D-DOPA, c is the UV absorption spectrum of D-Phe-MnO2 catalytically degrading L-DOPA in the enzyme kinetics experiment of the application for catalytically degrading 2,4-DP and L / D-DOPA, and d is the catalytic effect comparison diagram of the chiral enzyme and the natural laccase in the enzyme kinetics experiment of the application for catalytically degrading 2,4-DP and L / D-DOPA.

[0040] Figure 4 Vmax and Km obtained from the enzyme kinetics experiment of the application for catalytically degrading; wherein a is Vmax obtained from the enzyme kinetics experiment of the application for catalytically degrading 2,4-DP, b is Km obtained from the enzyme kinetics experiment of the application for catalytically degrading 2,4-DP, c is Km obtained from the enzyme kinetics experiment of the application for catalytically degrading L / D-DOPA, and d is Vmax obtained from the enzyme kinetics experiment of the application for catalytically degrading L / D-DOPA. DETAILED DESCRIPTION

[0041] The application will be further described below in conjunction with the drawings and specific examples, so that those skilled in the art can better understand the application and implement it, but the examples are not limiting to the application.

[0042] Example 1

[0043] Step (1), 0.3936 g of KMnO4 was dissolved in 8.5 mL of water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL of water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution, and stirred for 15 minutes.

[0044] Step (2), 1 mL of L-glutamic acid (Glu) solution (0.1 M) was quickly added to the solution, and stirred vigorously for 1 minute.

[0045] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (stirring vigorously) to form an emulsion.

[0046] Step (4), 3.34 mL of ethanol (EtOH) and 2 mL of L-glutamic acid (Glu) solution (0.1 M) were added to the emulsion, and stirred slightly at 50℃ for 45 min. After cooling to room temperature (25±5℃), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60℃ to obtain manganese dioxide nanoscale enzyme.

[0047] Example 2

[0048] Step (1), 0.3936 g KMn04was dissolved in 8.5 mL water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution and stirred for 15 minutes.

[0049] Step (2), 1 mL of L-glutamic acid (Glu) solution (0.1 M) was quickly added to the solution, and stirred vigorously for 1 minute.

[0050] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (stirred vigorously) to form an emulsion.

[0051] Step (4), 3.34 mL of EtOH and 2 mL of L-glutamic acid (Glu) solution (0.1 M) were added to the emulsion, and stirred slightly at 50 °C for 45 min. After cooling to room temperature (25 ± 5 °C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60 °C to obtain manganese dioxide nanoszyme.

[0052] Example 3

[0053] Step (1), 0.3936 g KMn04was dissolved in 8.5 mL water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution and stirred for 15 minutes.

[0054] Step (2), 1 mL of L-histidine (His) solution (0.1 M) was quickly added to the solution, and stirred vigorously for 1 minute.

[0055] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (stirred vigorously) to form an emulsion.

[0056] Step (4), 3.34 mL of EtOH and 2 mL of L-histidine (His) solution (0.1 M) were added to the emulsion, and stirred slightly at 50 °C for 45 min. After cooling to room temperature (25 ± 5 °C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60 °C to obtain manganese dioxide nanoszyme.

[0057] Example 4

[0058] Step (1), 0.3936 g KMn04was dissolved in 8.5 mL water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution and stirred for 15 minutes.

[0059] Step (2), 1 mL of D-histidine (His) solution (0.1 M) was quickly added to the solution, and stirred vigorously for 1 minute.

[0060] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (vigorous stirring) to form an emulsion.

[0061] Step (4), 3.34 mL of EtOH and 2 mL of D-Histidine (His) solution (0.1 M) was added to the emulsion, which was slightly stirred at 50 °C for 45 min. After cooling to room temperature (25 ± 5 °C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60 °C to obtain manganese dioxide nanoszyme.

[0062] Example 5

[0063] Step (1), 0.3936 g of KMnO4 was dissolved in 8.5 mL of water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL of water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution, and stirred for 15 minutes.

[0064] Step (2), 1 mL of L-Tyrosine (Ary) solution (0.1 M) was quickly added to the solution, and stirred vigorously for 1 minute.

[0065] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (vigorous stirring) to form an emulsion.

[0066] Step (4), 3.34 mL of EtOH and 2 mL of L-Tyrosine (Ary) solution (0.1 M) was added to the emulsion, which was slightly stirred at 50 °C for 45 min. After cooling to room temperature (25 ± 5 °C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60 °C to obtain manganese dioxide nanoszyme.

[0067] Example 6

[0068] Step (1), 0.3936 g of KMnO4 was dissolved in 8.5 mL of water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL of water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution, and stirred for 15 minutes.

[0069] Step (2), 1 mL of L-Tyrosine (Ary) solution (0.1 M) was quickly added to the solution, and stirred vigorously for 1 minute.

[0070] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (vigorous stirring) to form an emulsion.

[0071] Step (4), 3.34 mL of EtOH and 2 mL of D-tyrosine (Ary) solution (0.1 M) was added to the emulsion, stirred gently at 50 °C for 45 min. After cooling to room temperature (25 ± 5 °C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60 °C to obtain manganese dioxide nanoszyme.

[0072] Example 7

[0073] Step (1), 0.3936 g of KMn04was dissolved in 8.5 mL of water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL of water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution and stirred for 15 min.

[0074] Step (2), 1 mL of L-phenylalanine (Phe) solution (0.1 M) was quickly added to the solution, and stirred vigorously for 1 min.

[0075] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (stirred vigorously) to form an emulsion.

[0076] Step (4), 3.34 mL of EtOH and 2 mL of L-phenylalanine (Phe) solution (0.1 M) was added to the emulsion, stirred gently at 50 °C for 45 min. After cooling to room temperature (25 ± 5 °C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60 °C to obtain manganese dioxide nanoszyme.

[0077] Example 8

[0078] Step (1), 0.3936 g of KMn04was dissolved in 8.5 mL of water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL of water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution and stirred for 15 min.

[0079] Step (2), 1 mL of L-phenylalanine (Phe) solution (0.1 M) was quickly added to the solution, and stirred vigorously for 1 min.

[0080] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (stirred vigorously) to form an emulsion.

[0081] Step (4), 3.34 mL of EtOH and 2 mL of L-phenylalanine (Phe) solution (0.1 M) was added to the emulsion, stirred gently at 50 °C for 45 min. After cooling to room temperature (25 ± 5 °C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60 °C to obtain manganese dioxide nanoszyme.

[0082] Example 9

[0083] Step (1), 0.3936 g of KMn04was dissolved in 8.5 mL of water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL of water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution and stirred for 15 minutes.

[0084] Step (2), 1 mL of L-cysteine (Cys) solution (0.1 M) was quickly added to the solution and stirred vigorously for 1 minute.

[0085] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (stirring vigorously) to form an emulsion.

[0086] Step (4), 3.34 mL of EtOH and 2 mL of L-cysteine (Cys) solution (0.1 M) were added to the emulsion, which was stirred slightly at 50°C for 45 min. After cooling to room temperature (25±5°C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60°C to obtain manganese dioxide nanoszyme.

[0087] Example 10

[0088] Step (1), 0.3936 g of KMn04was dissolved in 8.5 mL of water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL of water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution and stirred for 15 minutes.

[0089] Step (2), 1 mL of L-cysteine (Cys) solution (0.1 M) was quickly added to the solution and stirred vigorously for 1 minute.

[0090] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (stirring vigorously) to form an emulsion.

[0091] Step (4), 3.34 mL of EtOH and 2 mL of L-cysteine (Cys) solution (0.1 M) were added to the emulsion, which was stirred slightly at 50°C for 45 min. After cooling to room temperature (25±5°C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60°C to obtain manganese dioxide nanoszyme.

[0092] Example 11

[0093] Step (1), 0.3936 g of KMn04was dissolved in 8.5 mL of water, 0.1736 g of manganese sulfate was dissolved in 1.5 mL of water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution and stirred for 15 minutes.

[0094] Step (2), 1 mL of L-cysteine (Cys) solution (0.1 M) was quickly added to the solution and stirred vigorously for 1 minute.

[0095] Step (3), 4.8 mL of KOH solution (0.1 M) was added to the solution (vigorous stirring) to form an emulsion.

[0096] Step (4), 3.34 mL EtOH and 2 mL L-Tryptophan (Tar) solution (0.1 M) were added to the emulsion, and stirred slightly at 50°C for 45 min. After cooling to room temperature (25±5°C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60°C to obtain manganese dioxide nanoszyme.

[0097] Example 12

[0098] Step (1), 0.3936 g KMnO4was dissolved in 8.5 mL water, and 0.1736 g manganese sulfate was dissolved in 1.5 mL water, then the manganese sulfate solution was added dropwise to the potassium permanganate solution and stirred for 15 min.

[0099] Step (2), 1 mL L-Tryptophan (Tar) solution (0.1 M) was quickly added to the solution, and stirred vigorously for 1 min.

[0100] Step (3), 4.8 mL KOH solution (0.1 M) was added to the solution (vigorous stirring) to form an emulsion.

[0101] Step (4), 3.34 mL EtOH and 2 mL D-Tryptophan (Tar) solution (0.1 M) were added to the emulsion, and stirred slightly at 50°C for 45 min. After cooling to room temperature (25±5°C), the precipitate was collected by centrifugation (4000 rpm, 2 min, 5 times) and dried at 60°C to obtain manganese dioxide nanoszyme.

[0102] Application Example 1

[0103] 4-AP (1 mg·mL -1 , 100 μL) and 2,4-DP (1 mg·mL -1 , 100 μL) solution were mixed with Tri-Hcl buffer (30 mM, pH 7.2, 700 μL). Then the aqueous solution of manganese dioxide nanoszyme prepared in each example (1 mg·mL -1 , 100 μL) was added. After reaction at room temperature, the mixture was centrifuged, and the absorbance of the supernatant at 510 nm was measured.

[0104] Application Example 2

[0105] L / D-DOPA (1 mg·mL -1, 100 μL) Tri-Hcl buffer (30 mM, pH 7.2, 800 μL) was mixed. Then the manganese dioxide nanoscale enzyme prepared in each example (1 mg·mL -1 was added. After reaction at room temperature, the mixture was centrifuged, and the absorbance of the supernatant at 475 nm was measured.

[0106] Effect evaluation 1

[0107] The chiral manganese dioxide nanoscale enzyme prepared in the application has a uniform structure and has a good degradation efficiency of phenolic pollutants compared with natural laccase. According to the enzyme kinetics experiment, the maximum reaction rate of the nanoscale enzyme synthesized by one kind of amino acid as a ligand is as high as 0.048±0.002 mM·min -1 In addition, the chiral nanoscale enzyme also has the ability to selectively catalyze chiral substrates. L-Phe-MnO2 in the application shows strong selectivity for L-DOPA, and D-Phe-MnO2 shows strong selectivity for D-DOPA.

[0108] Obviously, the above examples are only examples for the sake of clarity, and are not limited to the embodiments. For ordinary skilled persons in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the application.

Claims

1. A method for the preparation of chiral manganese dioxide nanozymes with high laccase activity and high selectivity, characterized by, The method comprises the following steps: S11: dissolving manganese sulfate and potassium permanganate in water, then adding part of amino acids to obtain a salt solution; S12: adding a base to the salt solution to form an emulsion; S13: adding the remaining amino acids and ethanol to the emulsion, and heating at 48-52℃ for 40-50 min to obtain a reaction solution; the amino acids in steps S11 and S13 are the same; S14: post-treating the reaction solution to obtain the chiral manganese dioxide nanoscale enzyme with high laccase activity and high selectivity; the amino acid is a left-handed amino acid or a right-handed amino acid; in step S11, the mass ratio of manganese sulfate to potassium permanganate is 0.15-0.2:0.35-0.4; the amino acid is an aqueous solution of amino acid with a concentration of 0.1 M.

2. The production method according to claim 1, wherein The molar ratio of the amino acids in steps S11 and S13 is 1:

2.

3. The production method according to claim 1, wherein The amino acid is selected from glutamic acid, histidine, tyrosine, phenylalanine, cysteine or tryptophan.

4. The production method according to claim 1, wherein In step S14, the post-treatment method is cooling to room temperature, solid-liquid separation and drying.

5. A chiral manganese dioxide nanoscale enzyme with high laccase activity and high selectivity prepared by the preparation method in any one of claims 1-4.

6. Application of the chiral manganese dioxide nanoscale enzyme with high laccase activity and high selectivity in claim 5 in catalytic degradation of 2,4-dichlorophenol.

7. Application of the chiral manganese dioxide nanoscale enzyme with high laccase activity and high selectivity in claim 5 in selective catalysis of L / D-dopa.

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