Chiral manganese dioxide nano-enzyme with high laccase activity and high selectivity as well as preparation method and application of chiral manganese dioxide nano-enzyme

Abstract

The invention belongs to the field of material chemistry, and particularly relates to a chiral manganese dioxide nano-enzyme with high laccase activity and high selectivity as well as a preparation method and application of the chiral manganese dioxide nano-enzyme. The method mainly comprises synthesis of chiral manganese dioxide nano-enzyme and optimization of synthesis conditions, a degradation method of 2, 4-dichlorophenol (2, 4-DP), catalysis of 2, 4-dichlorophenol by using the laccase-imitating property of the chiral manganese dioxide nano-enzyme, selective catalysis of chiral substrates, and selective catalysis of the chiral substrates L-DOPA and D-DOPA by using the chiral manganese dioxide nano-enzyme. The invention provides bionic laccase of which the catalytic efficiency is higher than that of natural laccase by more than 20 times and a synthetic method of chiral manganese dioxide nano-enzyme with selective catalytic capability, and has a very good application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of material chemistry, and specifically relates to a chiral manganese dioxide nanozyme with high laccase activity and high selectivity, and a preparation method and application thereof. Background Art

[0002] Phenolic pollutants such as 2,4-dichlorophenol are significantly harmful to the environment. It is a highly toxic and difficult to degrade organic pollutant that is widely distributed in the natural environment. 2,4-Dichlorophenol is toxic to aquatic organisms and has a negative impact on aquatic ecosystems. In the natural environment, 2,4-dichlorophenol is difficult to be degraded by microorganisms 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 natural laccase has poor stability and high cost, making it unsuitable for large-scale application in industry. Natural laccase has low specificity for substrates and can only catalyze the degradation of certain specific organic substances, which limits its scope of application.

[0003] A core challenge of asymmetric catalysis is how to design and synthesize highly selective catalysts 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 a variety of reactions, such as oxidation reactions, nucleophilic reactions, addition reactions, etc. Chiral manganese compounds can not only enhance the selectivity of catalytic reactions, but also provide efficient control over chiral centers, thereby achieving high-yield synthesis of chiral products. Summary of the invention

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

[0005] The present invention prepares a new type of nanozyme with laccase-like activity to catalytically degrade phenolic pollutants. A chiral manganese dioxide nanozyme is prepared using amino acids as chiral ligands for the efficient degradation of 2,4-DP and the catalytic conversion of chiral substrates. Compared with natural laccase, the nanozyme has higher catalytic efficiency and obvious selectivity for L / D-DOPA.

[0006] The present invention provides a method for preparing a chiral manganese dioxide nanozyme with high laccase activity and high selectivity, comprising the following steps:

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

[0008] S12: adding alkali to the salt solution and mixing to form an emulsion;

[0009] S13: adding the remaining amino acids and ethanol to the emulsion again, heating at 48-52° C. for reaction for 40-50 min to obtain a reaction solution; the amino acids in step S11 and step S13 are the same;

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

[0011] Preferably, the molar ratio of amino acids in step S11 and 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 L-amino acid or a D-amino acid.

[0014] Preferably, in step S11, the mass ratio of manganese sulfate to 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 acids are all aqueous solutions of amino acids with a concentration of 0.1M.

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

[0019] Furthermore, the drying temperature is 60°C.

[0020] Furthermore, the solid-liquid separation method is to collect the precipitate by centrifugation.

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

[0022] The present invention also provides a chiral manganese dioxide nanozyme with high laccase activity and high selectivity prepared by the above preparation method.

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

[0024] Catalytic reaction process: First, 1 mg / mL chiral manganese dioxide nanozyme solution reacted with a mixture of 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 and polymerization of chlorophenols. Chlorophenols are oxidized into free radicals or reactive quinones and other substances. These substances then couple with each other to form polymers, which reduce the solubility of these toxic substances and thus reduce their toxicity. This reaction mechanism includes the transfer of electrons and protons on phenols to form free radicals. In the reaction, one electron is transferred from the substrate to oxygen via laccase. During the oxidation process, two free radicals randomly combine to form dimers, which isomerize into stable aromatic ring products. In addition, dimers can also form free radicals, which can generate trimers or even polymers through a similar pathway to dimers.

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

[0027] S21: dissolving 4-aminobenzoic acid (4-AP) and 2,4-dichlorophenol (2,4-DP) in Tri-HCl buffer to obtain a mixed solution;

[0028] S22: Add the manganese dioxide nanozyme to the mixed solution, react at room temperature, and then centrifuge, and measure the absorbance of the supernatant at 510 nm.

[0029] The present invention also provides the use of the chiral manganese dioxide nanozyme with high laccase activity and high selectivity in the selective catalysis of L / D-DOPA (L / D-DOPA).

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

[0031] Catalytic reaction principle: The process of chiral manganese dioxide nanoparticles catalyzing the oxidation of L / D-DOPA depends on the stereo matching effect between its helical structure and the substrate. The catalytic process is divided into three stages: catechol is oxidized by a single electron to generate semiquinone free radicals, Mn 4+ The redox couple drives the formation of dopaquinone, which eventually polymerizes into helically arranged melanin.

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

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

[0034] S32: adding the chiral manganese dioxide nanozyme with high laccase activity and high selectivity to the mixed solution, reacting at room temperature and centrifuging, and measuring the absorbance of the supernatant at 475 nm.

[0035] The technical solution of the present invention has the following advantages over the prior art:

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

[0037] Figure 1 The figures are example effect diagrams; wherein, a is an example effect diagram of the present invention catalyzing 2,4-dichlorophenol, and b is an example effect diagram of the present invention catalyzing DOPA.

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

[0039] Figure 3Catalytic ability diagram and ultraviolet absorption spectrum diagram; wherein, a is the ability diagram of the chiral enzyme synthesized with different ligands screened in the enzyme kinetics experiment of catalytic degradation of 2,4-DP and L / D-DOPA of the present invention to catalyze the degradation of 2,4-DP, b is the ultraviolet absorption spectrum diagram of D-Phe-MnO2 catalyzing 2,4-DP in the enzyme kinetics experiment of catalytic degradation of 2,4-DP and L / D-DOPA of the present invention, c is the ultraviolet absorption spectrum diagram of D-Phe-MnO2 catalyzing L-DOPA in the enzyme kinetics experiment of catalytic degradation of 2,4-DP and L / D-DOPA of the present invention, d is the catalytic effect comparison diagram of the chiral enzyme and natural laccase in the enzyme kinetics experiment of catalytic degradation of 2,4-DP and L / D-DOPA of the present invention.

[0040] Figure 4 are Vmax and Km obtained from the kinetic experiment of catalytic degradation enzyme of the present invention; wherein, a is Vmax obtained from the kinetic experiment of catalytic degradation 2,4-DP enzyme of the present invention, b is Km obtained from the kinetic experiment of catalytic degradation 2,4-DP enzyme of the present invention, c is Km obtained from the kinetic experiment of catalytic degradation L / D-DOPA enzyme of the present invention; d is Vmax obtained from the kinetic experiment of catalytic degradation L / D-DOPA enzyme of the present invention. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0042] Example 1

[0043] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir 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), add 4.8 mL of KOH solution (0.1 M) 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 gently 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 nanozyme.

[0047] Example 2

[0048] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir for 15 minutes.

[0049] Step (2), quickly add 1 mL of D-glutamic acid (Glu) solution (0.1 M) into the solution and stir vigorously for 1 minute.

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

[0051] Step (4), 3.34 mL of EtOH and 2 mL of D-glutamic acid (Glu) solution (0.1 M) were added to the emulsion and gently 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 nanozyme.

[0052] Example 3

[0053] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir 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), add 4.8 mL of KOH solution (0.1 M) to the solution (vigorously stirred) 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 gently 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 nanozyme.

[0057] Example 4

[0058] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir 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), add 4.8 mL of KOH solution (0.1 M) to the solution (vigorously stirred) to form an emulsion.

[0061] Step (4), 3.34 mL of EtOH and 2 mL of D-histidine (His) solution (0.1 M) were added to the emulsion and gently 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 nanozyme.

[0062] Example 5

[0063] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir 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), add 4.8 mL of KOH solution (0.1 M) to the solution (vigorously stirred) to form an emulsion.

[0066] Step (4), 3.34 mL of EtOH and 2 mL of L-tyrosine (Ary) solution (0.1 M) were added to the emulsion and gently 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 nanozyme.

[0067] Example 6

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

[0069] Step (2), quickly add 1 mL of D-tyrosine (Ary) solution (0.1 M) into the solution and stir vigorously for 1 minute.

[0070] Step (3), add 4.8 mL of KOH solution (0.1 M) to the solution (vigorously stirred) to form an emulsion.

[0071] Step (4), 3.34 mL of EtOH and 2 mL of D-tyrosine (Ary) solution (0.1 M) were added to the emulsion and gently 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 nanozyme.

[0072] Example 7

[0073] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir for 15 minutes.

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

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

[0076] Step (4), 3.34 mL of EtOH and 2 mL of L-phenylalanine (Phe) solution (0.1 M) were added to the emulsion and gently 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 nanozyme.

[0077] Example 8

[0078] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir for 15 minutes.

[0079] Step (2), quickly add 1 mL of D-phenylalanine (Phe) solution (0.1 M) into the solution and stir vigorously for 1 minute.

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

[0081] Step (4), 3.34 mL of EtOH and 2 mL of D-phenylalanine (Phe) solution (0.1 M) were added to the emulsion and gently 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 nanozyme.

[0082] Example 9

[0083] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir 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), add 4.8 mL of KOH solution (0.1 M) to the solution (vigorously stirred) 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 and gently 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 nanozyme.

[0087] Example 10

[0088] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir for 15 minutes.

[0089] Step (2), quickly add 1 mL of D-cysteine ​​(Cys) solution (0.1 M) into the solution and stir vigorously for 1 minute.

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

[0091] Step (4), 3.34 mL of EtOH and 2 mL of D-cysteine ​​(Cys) solution (0.1 M) were added to the emulsion and gently 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 nanozyme.

[0092] Embodiment 11

[0093] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir for 15 minutes.

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

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

[0096] Step (4), 3.34 mL of EtOH and 2 mL of L-tryptophan (Tar) solution (0.1 M) were added to the emulsion and gently 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 nanozyme.

[0097] Example 12

[0098] Step (1), dissolve 0.3936 g of KMnO4 in 8.5 mL of water, dissolve 0.1736 g of manganese sulfate in 1.5 mL of water, then add the manganese sulfate solution dropwise to the potassium permanganate solution and stir for 15 minutes.

[0099] Step (2), quickly add 1 mL of D-tryptophan (Tar) solution (0.1 M) into the solution and stir vigorously for 1 minute.

[0100] Step (3), add 4.8 mL of KOH solution (0.1 M) to the solution (vigorously stirred) to form an emulsion.

[0101] Step (4), 3.34 mL of EtOH and 2 mL of D-tryptophan (Tar) solution (0.1 M) were added to the emulsion and gently 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 nanozyme.

[0102] Application Example 1

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

[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 nanozyme (1 mg mL -1 The reaction was carried out at room temperature, the mixture was centrifuged, and the absorbance of the supernatant was measured at 475 nm.

[0106] Effect evaluation 1

[0107] The present invention prepares a chiral manganese dioxide nanozyme with uniform structure, which has better degradation efficiency of phenolic pollutants than natural laccase. According to enzyme kinetic experiments, the maximum reaction rate of the nanozyme synthesized with one amino acid as a ligand is as high as 0.048±0.002mM·min -1 In addition, the chiral nanozyme also has the ability to selectively catalyze chiral substrates. The L-Phe-MnO2 in the present invention shows a strong selectivity for L-DOPA, while the D-Phe-MnO2 shows a strong selectivity for D-DOPA.

[0108] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for preparing a chiral manganese dioxide nanozyme with high laccase activity and high selectivity, characterized in that: The steps include: S11: dissolving manganese sulfate and potassium permanganate in water, adding part of amino acids and mixing to obtain a salt solution; S12: adding alkali to the salt solution and mixing to form an emulsion; S13: adding the remaining amino acids and ethanol to the emulsion again, heating at 48-52° C. for reaction for 40-50 min to obtain a reaction solution; the amino acids in step S11 and step S13 are the same; S14: post-treating the reaction solution to obtain the chiral manganese dioxide nanozyme with high laccase activity and high selectivity.

2. The preparation method according to claim 1, characterized in that The molar ratio of amino acids in step S11 and step S13 is 1:

2.

3. The preparation method according to claim 1, characterized in that: The amino acid is selected from glutamic acid, histidine, tyrosine, phenylalanine, cysteine ​​or tryptophan.

4. The preparation method according to claim 1, characterized in that: The amino acid is a left-handed amino acid or a right-handed amino acid.

5. The preparation method according to claim 1, characterized in that: In the step S11, the mass ratio of manganese sulfate to potassium permanganate is 0.15-0.2:0.35-0.

4.

6. The preparation method according to claim 1, characterized in that: The amino acids are all aqueous solutions of amino acids with a concentration of 0.1M.

7. The preparation method according to claim 1, characterized in that: In step S14, the post-treatment method is cooling to room temperature, solid-liquid separation, and drying.

8. A chiral manganese dioxide nanozyme with high laccase activity and high selectivity prepared by the preparation method as described in any one of claims 1 to 7.

9. Use of the chiral manganese dioxide nanozyme with high laccase activity and high selectivity as described in claim 8 in catalytic degradation of 2,4-dichlorophenol.

10. Use of the chiral manganese dioxide nanozyme with high laccase activity and high selectivity according to claim 8 in selective catalysis of L / D-DOPA.

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