Preparation method and application of polyacid / hydrotalcite composite mimic enzyme
By preparing P2W18O62/CoAl-LDH composite materials, the problems of insufficient stability and catalytic activity of polyoxometalates in hydrotalcite composite materials were solved, enabling rapid and sensitive detection of ascorbic acid, which is applicable to the field of biosensor technology.
Patent Information
- Application Number
- CN202511827859.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-03-20
AI Technical Summary
Existing polyoxometalates face problems such as poor stability, high solubility, and small specific surface area in practical applications, resulting in low catalytic efficiency. Furthermore, the interaction between polyoxometalates and hydrotalcite in polyoxometalate/hydrotalcite composites is weak, leading to poor catalytic activity and making it difficult to achieve rapid and sensitive detection of ascorbic acid.
By preparing P2W18O62/CoAl-LDH composite material, polyoxometalates are combined with layered hydrotalcite materials. The P2W18O62/CoAl-LDH composite enzyme was prepared in aqueous phase using a double-drop co-precipitation method and a hydrothermal synthesis method. The enzyme was then used to detect H2O2 and AA in the colorimetric reaction of 3,3',5,5'-tetramethylbenzidine (TMB).
Rapid and sensitive detection of ascorbic acid was achieved, with a linear detection range of 10-50 µmol/L and a detection limit of 12.5 µmol/L. The material also exhibited excellent selectivity and catalytic activity in actual fruit samples.
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Figure CN121695902A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of biosensor technology, and relates to a method for preparing and applying a polyacid / hydrotalcite composite mimic enzyme. Background Technology
[0002] Ascorbic acid (AA) is found in the human body, food, and pharmaceuticals. AA is an intracellular antioxidant that effectively scavenge free radicals in the body and reduce oxidative stress damage to cells. AA is highly unstable, making it easily destroyed by oxidation during food processing. Due to its widespread use in food and clinical medicine, the detection of its content is extremely important. Methods for detecting AA mainly include chemical analysis, chromatography, electrochemical methods, and colorimetric detection. Colorimetric detection of AA is an optical analysis method based on its reducing properties and is commonly used for the rapid detection of AA content in biological samples.
[0003] Enzyme-mimicking colorimetric sensing methods have attracted much attention due to their low cost and ease of operation. Colorimetric sensing relies on changes in the system's color to transmit information. Colorimetric sensing technology can typically achieve sample detection and analysis in a short time, improving the efficiency of experimental sample detection. Among various enzyme mimics, polyoxometalates are a unique class of inorganic metal-oxygen cluster compounds with rapid and reversible multi-electron redox capabilities. However, polyoxometalates face challenges in practical applications, such as poor stability, high solubility, and small specific surface area, which limit their catalytic efficiency. Hydrotalcite, a two-dimensional anionic layered material, possesses interlayer anion exchangeability, high specific surface area, and structural stability, making it an ideal support material. Combining polyoxometalates with hydrotalcite can solve the problem of their easy solubility. Currently, existing methods for preparing polyacid / hydrotalcite composites still have many shortcomings. In some methods, the interaction between polyacid and hydrotalcite in the composite material is weak, resulting in the loss of polyacid and poor catalytic activity. Therefore, it is urgent to explore a method for preparing a composite enzyme with strong interaction between polyacid and hydrotalcite to improve the catalytic performance of the composite material and achieve rapid and sensitive detection of AA. Summary of the Invention
[0004] To overcome the shortcomings of existing technologies, this invention provides a method for preparing and applying a polyacid / hydrotalcite composite mimic enzyme. This invention utilizes the preparation of P2W... 18 O 62 A / CoAl-LDH composite material was used in the colorimetric reaction of 3,3',5,5'-tetramethylbenzidine (TMB) to achieve the detection of H2O2 and AA. AA acts as a reducing agent in the reaction system, reducing the blue oxTMB to colorless TMB. Based on this, a rapid and sensitive TMB / H2O2 / P2W reaction was established. 18 O 62The / CoAl-LDH colorimetric sensing system was used to detect AA. The linear detection range for AA was 10–50 µmol / L, and the detection limit was 12.5 µmol / L. This sensing system exhibited excellent selectivity and also supported the TMB / H₂O₂ / P₂W... 18 O 62 The / CoAl-LDH sensing system was used to detect AA in actual fruit samples. The prepared composite enzyme mimicry combines the high catalytic activity of polyacids with the two-dimensional layered structure and high stability of hydrotalcite.
[0005] The above-mentioned objective of this invention is achieved through the following technical solution: A method for preparing a polyacid / hydrotalcite complex mimic enzyme includes the following steps: S1. CoAl-LDH was prepared by a double-drop co-precipitation method under alkaline conditions using aluminum nitrate and cobalt nitrate as raw materials; S2. K6P2W was prepared by heating under reflux in acidic conditions using sodium tungstate as a raw material. 18 O 62 ; S3. The K6P2W prepared in step S2... 18 O 62 Dissolving in deionized water yields K6P2W 18 O 62 The solution, the CoAl-LDH prepared in step S1, is added to the above K6P2W. 18 O 62 P2W was prepared in solution. 18 O 62 / CoAl-LDH complex mimic enzyme.
[0006] Furthermore, in step S1, the pH of the alkaline conditions is 10-11.
[0007] Furthermore, in step S1, the molar ratio of cobalt nitrate to aluminum nitrate is 3:1-4:1.
[0008] Furthermore, in step S2, during the heating and reflux process, the reaction temperature is 85-95℃ and the reflux time is 5-13h.
[0009] Furthermore, in step S3, K6P2W 18 O 62 The mass ratio of the substance to the CoAl-LDH is 0.2:1 to 0.5:1.
[0010] Furthermore, in step S3, K6P2W 18 O 62 The concentration of the solution is 1 mmol / L.
[0011] More specifically, in step S1, CoAl-LDH is prepared using the double-drop co-precipitation method; the specific steps are as follows: Weigh out Al(NO3)3·9H2O and Co(NO3)2·6H2O, dissolve them in H2O, and sonicate for 10 min to obtain solution A. Dissolve NaOH and Na2CO3 in H2O to obtain solution B. Add solutions A and B dropwise to a three-necked flask simultaneously while stirring, maintaining a pH range of 10 ± 0.2. After the addition of solutions A and B is complete, stir thoroughly at 1500-2000 rpm for 30 min to allow co-precipitation. Then transfer the three-necked round-bottom flask to a constant temperature water bath and age it at 60-70℃ for 24 h. Filter, wash, and dry to obtain the product.
[0012] The molar ratio of Al(NO3)3.9H2O and Co(NO3)2.6H2O is 1:3-1:4.
[0013] The molar ratio of NaOH to Na2CO3 is 15:1-16:1.
[0014] More specifically, in step S2, K6P2W 18 O 62 The synthesis method is as follows: Na₂WO₄·2H₂O is added to a round-bottom flask containing deionized water, and the solution is heated to boiling. 85% (w / w) H₃PO₄ is added, and the mixture is heated under reflux for 8-10 hours. After cooling, KCl is added and stirred to obtain a light green precipitate, which is then filtered. The precipitate is dissolved in hot water and recrystallized overnight at 3-5°C. Yellow crystals precipitate; the crystals are collected and dried at 75-85°C to obtain K₆P₂W₄. 18 O 62 .
[0015] The molar ratio of Na2WO4·2H2O to H3PO4 is 0.1:1-0.2:1.
[0016] The molar ratio of Na2WO4·2H2O to KCl is 0.2:1-0.3:1.
[0017] More specifically, in step S3, P2W 18 O 62 The synthesis method of / CoAl-LDH is as follows: K6P2W 18 O 62 Dissolve in 15-20 mL H2O, then add CoAl-LDH to the above polyoxometalate solution, sonicate for 2-3 h, stir at 55℃-65℃ for 10-12 h, centrifuge, wash, and dry to obtain P2W. 18 O 62 / CoAl-LDH complex mimic enzyme.
[0018] Among them, K6P2W 18 O 62 The mass ratio of CoAl-LDH is 0.2:1-0.5:1.
[0019] The present invention also seeks protection for the application of the composite mimic enzyme prepared by the above preparation method in the preparation of a biosensor for detecting the concentration of AA in fruit samples.
[0020] The advantages of this invention compared to the prior art are: (1) In this invention, a polyoxometalate with redox activity is combined with CoAl-LDH with a two-dimensional layered structure. The synergistic effect of the two enhances the catalytic activity, making it superior to K6P2W in the colorimetric reaction of AA. 18 O 62 The catalytic activity of CoAl-LDH.
[0021] (2) The double-drop coprecipitation method and hydrothermal synthesis method used in this invention are simple, mild, do not require complex and expensive instruments and equipment, and the reaction is carried out in the aqueous phase.
[0022] (3) The composite material prepared by the present invention achieves charge balance, size matching and multiple interactions between the host and the guest by inserting POMs into the interlayer structure of LDHs, thereby giving the material better performance.
[0023] (4) P2W prepared in this invention 18 O 62 The catalytic activity of the CoAl-LDH complex mimic enzyme is stronger than that of K6P2W alone. 18 O 62 And CoAl-LDH materials, which can be applied in the field of biosensor technology. A P2W-based... 18 O 62 The AA colorimetric sensing platform based on CoAl-LDH material is expected to provide new materials and methods for the field of colorimetric sensing. Attached Figure Description
[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Figure 1 The P2W prepared in Example 3 of this invention 18 O 62 / CoAl-LDH, CoAl-LDH prepared in Example 1, and K6P2W prepared in Example 2 18 O 62 The infrared spectrum.
[0025] Figure 2 The P2W prepared in Example 3 of this invention 18 O 62 XPS spectrum of / CoAl-LDH.
[0026] Figure 3 The P2W prepared in Example 3 of this invention 18 O 62 Transmission electron microscopy image of / CoAl-LDH.
[0027] Figure 4 Figure A shows the UV-Vis absorption curves, where Figure A is the K6P2W prepared in Example 2 of this invention. 18 O 62 P2W prepared in Example 3 18 O 62 / CoAl-LDH, the CoAl-LDH prepared in Example 1, and the UV-Vis absorption curves in the TMB / H2O2 system. Figure B shows the UV-Vis absorption curves of TMB, H2O2, TMB / H2O2, and P2W. 18 O 62 / CoAl-LDH, TMB / P2W 18 O 62 / CoAl-LDH、H2O2 / P2W 18 O 62 / CoAl-LDH, TMB / H2O2 / P2W 18 O 62 A comparison of the UV-Vis absorption curves of the seven systems / CoAl-LDH.
[0028] Figure 5 The P2W prepared in Example 3 of this invention 18 O 62 The UV-Vis absorption curves of / CoAl-LDH under H2O2 conditions and the relationship between the increase in absorption intensity at 652 nm and different H2O2 concentrations are shown in Figure A. Figure A shows the P2W prepared in Example 3 of this invention. 18 O 62 The UV-Vis absorption curves of / CoAl-LDH under 2μM-70μM H2O2 conditions. Figure B shows the P2W prepared in Example 3 of this invention. 18 O 62 The graph shows the relationship between the increase in absorption intensity of / CoAl-LDH at 652 nm and different H2O2 concentrations.
[0029] Figure 6 The P2W prepared in Example 3 of this invention 18 O 62The UV-Vis absorption of / CoAl-LDH under different concentrations of AA. Figure A shows the P2W prepared in Example 3 of this invention. 18 O 62 The UV-Vis absorption curves of / CoAl-LDH under the condition of 10-50 µmol / LAA are shown in Figure B, which shows the P2W prepared in Example 3 of this invention. 18 O 62 The graph shows the relationship between the increase in absorption intensity of / CoAl-LDH at 652 nm and different AA concentrations.
[0030] Figure 7 For example 4, TMB / H2O2 / P2W 18 O 62 The UV absorbance values of the / CoAl-LDH sensing system when coexisting with different selective substances are shown in the graphs. The systems contain KCl, NaCl, glycine, L-lysine, L-hydroxyproline, L-aspartic acid, L-methionine, L-histidine, urea, and citric acid. Detailed Implementation
[0031] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.
[0032] Example 1 Weigh 1.1254 g (0.003 mol) Al(NO3)3·9H2O and 2.6193 g (0.009 mol) Co(NO3)2·6H2O and dissolve them in 60 mL of H2O. Sonicate for 10 min to obtain salt solution A. Prepare mixed alkali solution B: Dissolve 0.96 g NaOH and 0.159 g Na2CO3 in 60 mL of H2O. Add salt solution A and mixed alkali solution B dropwise to a three-necked flask simultaneously while stirring. Maintain a pH range of 10 ± 0.2. After the addition of salt solution A and mixed alkali solution B is complete, stir at 1500-2000 rpm for 30 min to allow co-precipitation. Then, transfer the three-necked round-bottom flask to a constant temperature water bath (65℃) for aging for 24 h. Filter, wash, and dry to obtain the product CoAl-LDH.
[0033] Example 2 Add 10 g of Na₂WO₄·2H₂O to a round-bottom flask containing 35 mL of H₂O, and heat the solution to boiling. Add 15 mL of 85% H₃PO₄ and heat under reflux for 8 h. Cool, add 10 g of KCl and stir to obtain a light green precipitate, which is then filtered. Dissolve the precipitate in a small amount of hot water and recrystallize overnight at 5 °C. Yellow crystals precipitate; collect the crystals and dry at 80 °C to obtain the product K₆P₂W₄. 18 O 62 .
[0034] Example 3 0.069g of K6P2W prepared in Example 2 was used. 18 O 62 Dissolve 0.2143 g of the CoAl-LDH prepared in Example 1 in 15 mL of H2O. Add the above polyoxometalate solution, sonicate for 2 h, stir at 60 °C for 12 h, centrifuge, wash, and grind the dried block product in an agate mortar to obtain P2W. 18 O 62 / CoAl-LDH complex mimic enzyme. The synthesized material was structurally characterized. Figure 1 , Figure 2 , Figure 3 P2W can be observed 18 O 62 / CoAl-LDH material at 1635cm -1 The absorption peak at 1382 cm⁻¹ can be attributed to the -OH bending vibration of interlayer water. -1 The absorption peak that appears is CO3 2－ The asymmetric stretching vibration of CO was observed. The XPS full spectrum showed characteristic peaks for Co 2p, Al 2p, P 2p, W 4f, and O 1s, indicating that the prepared sample contained Co, Al, O, and trace amounts of P and W. TEM analysis confirmed that the synthesized material exhibited a plate-like structure. This plate-like structure exposes more active sites, promoting the catalytic process.
[0035] Application Comparative Example 1 Using the CoAl-LDH material prepared in Example 1 as a control sample, a TMB / H2O2 / CoAl-LDH sensing system was constructed, and its ultraviolet-visible absorption spectrum was measured in the same manner as in Application Example 1.
[0036] Application Comparative Example 2 The K6P2W prepared in Example 2 18 O 62 As a control sample, TMB / H2O2 / K6P2W was constructed. 18 O 62 The sensing system follows the same steps as in Application Example 1. For example... Figure 4Figure A shows a comparison of the colorimetric detection results of H2O2 in the three reaction systems in the presence of TMB. It can be seen that P2W 18 O 62 The catalytic performance of the CoAl-LDH composite material is stronger than that of CoAl-LDH and K6P2W. 18 O 62 These two materials. The P2W prepared in this invention. 18 O 62 The catalytic activity of the CoAl-LDH complex mimic enzyme was higher than that of CoAl-LDH and K6P2W. 18 O 62 These two enzyme mimics fully demonstrate that the combination of POMs and LDH produces a significant synergistic catalytic effect.
[0037] Application Example 1 The P2W prepared in Example 3 18 O 62 / CoAl-LDH acts as a peroxidase mimicking enzyme to catalyze the oxidation reaction of H2O2 with the substrate TMB. The reaction system contains 20 μL of 30 wt% H2O2, 400 μL of TMB, and 100 μL of P2W. 18 O 62 / CoAl-LDH solution, 1000 μL phosphate buffer solution at pH=3. Construct TMB / H₂O₂ / P₂W 18 O 62 The reaction system of / CoAl-LDH was reacted at room temperature for 30 min, and then placed in a UV-Vis absorption spectrometer to measure its UV-Vis absorption spectrum.
[0038] Application Example 2 To determine the TMB / H2O2 / P2W constructed in Application Example 1 18 O 62 The feasibility of the / CoAl-LDH sensing system was investigated, and six additional control systems were set up to compare it with TMB / H2O2 / P2W. 18 O 62 A comparison was made between the / CoAl-LDH system, namely TMB, H2O2, TMB / H2O2, and P2W. 18 O 62 / CoAl-LDH, TMB / P2W 18 O 62 / CoAl-LDH、H2O2 / P2W 18 O 62 / CoAl-LDH, keeping the total reaction volume of all systems consistent, followed the same procedure as in Application Example 1, and measured its UV absorption. Results are as follows: Figure 4 As shown in Figure B, compared to TMB / H2O2 / P2W 18O 62 The / CoAl-LDH sensing system, including systems containing only TMB, H2O2, and TMB / H2O2, does not exhibit a significant absorption peak at 652 nm. This indicates that P2W 18 O 62 / CoAl-LDH composite materials can be used as enzyme mimics for catalyzing colorimetric reactions of H2O2.
[0039] Application Example 3 The P2W prepared in Example 3 18 O 62 / CoAl-LDH complex mimic enzyme is used for colorimetric detection of H2O2. Within a certain range, the relationship between the intensity of the product color and the change in H2O2 concentration is explored. Figure 5 Figure A in the diagram is P2W 18 O 62 UV-Vis absorption curves of / CoAl-LDH at different concentrations of H2O2. The H2O2 concentration varied in the range of 2-70 µmol / L. The absorption intensity gradually increased with increasing H2O2 concentration. Figure 5 Figure B in the diagram is P2W 18 O 62 The relationship between H2O2 concentration and absorption intensity increment at 652 nm for / CoAl-LDH material was plotted, and the fitted linear equation was y = 0.00172x + 0.1522 (R²). 2 =0.985). The limit of detection can be calculated using the formula LOD = 3σ / k, where σ represents the standard deviation of the blank sample and k is the slope of the calibration curve for H2O2. The calculated limit of detection is 3.48 µmol / L.
[0040] Application Example 4 Ascorbic acid (AA) has reducing properties, thus turning the oxidized form of TMB colorless. Based on Application Example 1, AA was added, and the TMB / H₂O₂ / P₂W constructed in Application Example 1 was tested. 18 O 62 The / CoAl-LDH sensing system detects ascorbic acid by measuring changes in UV absorbance at 652 nm. The reaction system contains 20 μL of AA, 20 μL of 30 wt% H2O2, 400 μL of TMB, 100 μL of a simulated enzyme solution, and 1000 μL of phosphate buffer solution at pH 3. Figure 6 Figure A in the diagram represents TMB / H2O2 / P2W. 18 O 62 UV-Vis absorption curves of the / CoAl-LDH sensing system under different concentrations of AA Figure 6Figure B shows the relationship between the increase in absorption intensity at 652 nm and different AA concentrations for this system. The AA concentration varies from 10-50 µmol / L, and it can be seen that the absorption intensity gradually decreases with increasing AA concentration. Figure 6 The linear equation obtained from the fitting result in Figure B is y = 0.0037x - 0.03681 (R²). 2 =0.992). The detection limit was calculated to be 12.5 µmol / L using the formula LOD=3σ / k, and the linear detection range for AA was 10-50 µmol / L.
[0041] Investigating TMB / H2O2 / P2W 18 O 62 The CoAl-LDH sensing system exhibited selectivity for amino acids (AA). KCl, NaCl, glycine, L-lysine, L-hydroxyproline, L-aspartic acid, L-methionine, L-histidine, urea, and citric acid were added in the absence of AA. The UV absorbance at 652 nm was measured for each of these systems. The system containing AA was used as a control; the concentrations of other interfering substances were five times that of AA. Figure 7 As shown, it can be seen that the system containing AA has a value of ΔA. 652nm ΔA compared to other interference systems 652nm It is much higher. This further confirms the excellent selectivity of this sensing system.
[0042] The above test results fully demonstrate that the preparation method of the polyoxometalate / hydrotalcite composite mimic enzyme provided by this invention successfully immobilizes POMs in the LDH interlayer, and the obtained P2W 18 O 62 The / CoAl-LDH composite material not only has high catalytic activity but also high selectivity, enabling the detection of AA concentration in fruit samples and solving a key problem in the practical application of POMs-mimicking enzymes.
[0043] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.
Claims
1. A method for preparing a polyacid / hydrotalcite composite mimic enzyme, characterized in that, Includes the following steps: S1. CoAl-LDH was prepared by a double-drop co-precipitation method under alkaline conditions using aluminum nitrate and cobalt nitrate as raw materials; S2. K6P2W was prepared by heating under reflux in acidic conditions using sodium tungstate as a raw material. 18 O 62 ; S3. The K6P2W prepared in step S2... 18 O 62 Dissolving in deionized water yields K6P2W 18 O 62 The solution, the CoAl-LDH prepared in step S1, is added to the above K6P2W. 18 O 62 P2W was prepared in solution. 18 O 62 / CoAl-LDH complex mimic enzyme.
2. The method for preparing a polyacid / hydrotalcite composite mimic enzyme as described in claim 1, characterized in that, In step S1, the pH of the alkaline conditions is 10-11.
3. The method for preparing a polyacid / hydrotalcite composite mimic enzyme as described in claim 1, characterized in that, In step S1, the molar ratio of cobalt nitrate to aluminum nitrate is 3:1-4:
1.
4. The method for preparing a polyacid / hydrotalcite composite mimic enzyme as described in claim 1, characterized in that, In step S2, during the heating and reflux process, the reaction temperature is 85-95℃ and the reflux time is 5-13h.
5. The method for preparing a polyacid / hydrotalcite composite mimic enzyme as described in claim 1, characterized in that, In step S3, K6P2W 18 O 62 The mass ratio of the substance to the CoAl-LDH is 0.2:1-0.5:
1.
6. The method for preparing a polyacid / hydrotalcite composite mimic enzyme as described in claim 1, characterized in that, In step S1, CoAl-LDH is prepared using the double-drop co-precipitation method; the specific steps are as follows: Weigh out Al(NO3)3·9H2O and Co(NO3)2·6H2O and dissolve them in H2O. Sonicate for 10 min to obtain solution A. Dissolve NaOH and Na2CO3 in H2O to obtain solution B. Add solutions A and B dropwise to a three-necked flask simultaneously while stirring. Maintain a pH range of 10 ± 0.
2. After the addition of solutions A and B is complete, stir thoroughly at 1500-2000 rpm for 30 min to allow co-precipitation. Then, transfer the three-necked round-bottom flask to a constant temperature water bath and age it at 60℃-70℃ for 24 h. Filter, wash, and dry to obtain the product. The molar ratio of Al(NO3)3·9H2O and Co(NO3)2·6H2O is 1:3-1:4; The molar ratio of NaOH to Na2CO3 is 15:1-16:
1.
7. The method for preparing a polyacid / hydrotalcite composite mimic enzyme as described in claim 1, characterized in that, In step S2, K6P2W 18 O 62 The specific steps of the synthesis method are as follows: Add Na2WO4·2H2O to a round-bottom flask containing deionized water and heat the solution to boiling; add 85% H3PO4 by mass and heat under reflux for 8-10 hours. Cool, add KCl and stir to obtain a light green precipitate, filter; dissolve in hot water, recrystallize overnight at 3℃-5℃. Yellow crystals precipitate, collect the crystals, and dry at 75℃-85℃ to obtain K6P2W. 18 O 62 ; The molar ratio of Na₂WO₄·2H₂O to H₃PO₄ is 0.1:1-0.2:1; The molar ratio of Na2WO4·2H2O to KCl is 0.2:1-0.3:
1.
8. The method for preparing a polyacid / hydrotalcite composite mimic enzyme as described in claim 1, characterized in that, In step S3, P2W 18 O 62 The synthesis method of / CoAl-LDH is as follows: K6P2W 18 O 62 Dissolve in 15-20 mL H2O, then add CoAl-LDH to the above polyoxometalate solution, sonicate for 2-3 h, stir at 55℃-65℃ for 10-12 h, centrifuge, wash, and dry to obtain P2W. 18 O 62 / CoAl-LDH complex mimic enzyme; Among them, K6P2W 18 O 62 The mass ratio of CoAl-LDH is 0.2:1-0.5:
1.
9. The application of the composite mimic enzyme prepared by the preparation method according to any one of claims 1-8 in the preparation of a biosensor for detecting the concentration of AA in fruit samples.