Metal oxide nanozyme confined in MOF, method for preparing the same, and method for detecting ascorbic acid

Abstract

To provide a metal oxide nanozyme for solving the problem of insufficient enzyme activity caused by easy aggregation of small and medium sized nanozymes, and to provide a method for producing the same.SOLUTION: To provide a metal oxide nanozyme confined in an MOF, a method for producing the same, and a method for detecting ascorbic acid. The metal oxide nanozyme confined in the MOF is a complex formed by ZnIrOx clusters and ZnIrMOFs, and the ZnIrOx clusters are uniformly grown on the surface of the ZnIrMOFs. The metal-oxide nanozyme confined in the MOF can catalyze the chemiluminescent reaction of oxidizing luminol in the H2O2, thereby achieving highly sensitive and specific detection of ascorbic acid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present application is in the field of nanozyme material fabrication and colorimetric detection, and specifically relates to MOF-confined metal oxide nanozymes and their fabrication methods, as well as methods for detecting ascorbic acid. [Background technology]

[0002] Ascorbic acid (AA), also known as vitamin C, is a common water-soluble organic compound and an essential micronutrient that plays a crucial role in metabolic processes in humans and animals. It is often added to foods, beverages, and pharmaceutical preparations as an antioxidant. AA deficiency can lead to scurvy, while excessive AA intake can cause stomach cramps, urinary stones, and diarrhea. Therefore, rapid, sensitive, and selective detection of AA content is of great importance in medical measurement and diagnosis. Currently, analytical techniques such as fluorescence, colorimetry, electrochemistry, electrochemiluminescence, and chemiluminescence have been developed to efficiently detect AA. Among these, chemiluminescence (CL) has the advantages of requiring no excitation source and corresponding spectroscopic system, simple equipment, fast response, low cost, low background signal, and a wide linear range, significantly improving detection sensitivity. The development of a simple and efficient CL sensor is crucial for quantitative detection of AA.

[0003] Natural enzymes can specifically and efficiently catalyze various biochemical reactions under mild conditions. Peroxidase, in particular, can catalyze H2O2-mediated chemiluminescence reactions, making them widely used in the fabrication of various sensing systems for detecting AA. However, their applications are severely limited by the inherent thermoinstability of natural enzymes, their high cost, and limited natural sources. For these reasons, researchers have recently focused on developing various nanomaterials as artificial enzyme mimics, offering advantages such as low cost, high stability, tunable structure, and established synthetic routes. However, the majority of nanozyme-like enzymes have relatively low enzyme-like activity and poor stability, posing many challenges for bioanalytical applications. Reducing the size of nanozymes is an effective way to improve their catalytic performance, but it also increases their surface free energy, causing nanozyme aggregation and loss of catalytic activity. Metal-organic frameworks are a type of porous crystalline material formed by self-assembly through coordination bonds between metal ions and organic ligands. Their tunable nature allows them to form internal cavities of different sizes. Confining nanocatalysts in these cavities exerts a strong constraint on the physical and chemical states of the catalytic system, enabling precise tuning and control of catalytic performance, thereby improving reaction selectivity and efficiency. Therefore, we utilize the confinement effect of MOFs to control the in situ formation of nanozymes, thereby providing good control over their size, good stability, and efficient enzyme-like activity.

[0004] Based on this, we developed MOF-confined ZnIrOx cluster composites (ZnIrOx / ZnIrMOFs) as efficient oxidase- and peroxidase-like enzymes. Characterization by spherical aberration-corrected transmission electron microscopy revealed that the ZnIrOx clusters are relatively small and grow uniformly on the surface of the ZnIrMOFs, with Zn atoms doped into the IrOx lattice. The presence of Zn increases the crystallinity of the MOF phase, leading to better dispersion of the ZnIrOx clusters and optimizing and tuning the electronic structure of the metal atoms. The ZnIrOx / ZnIrMOFs exhibit excellent catalytic performance, promoting the redox reaction of the chemiluminescent substrate luminol with H2O2 to generate a luminescent signal. Furthermore, by utilizing their quenching effect on the AA chemiluminescence, they achieve highly sensitive and specific detection of AA. Summary of the Invention [Problem to be solved by the invention]

[0005] To solve the problem of insufficient enzyme activity due to the tendency of small and medium-sized nanozymes to aggregate in the prior art, this application provides a metal oxide nanozyme confined in an MOF, a method for producing the same, and a method for detecting ascorbic acid. The MOF-confined metal oxide nanozyme is a MOF / metal oxide cluster complex, and has efficient multi-enzyme activity as an oxidase-like enzyme and a peroxidase-like enzyme. A chemiluminescence sensor fabricated using ZnIrOx / ZnIrMOFs as a catalyst can detect the concentration of ascorbic acid in food with high sensitivity and specificity. [Means for solving the problem]

[0006] The present invention is realized by the following technical solution.

[0007] According to the MOF-confined metal oxide nanozyme, the MOF-confined metal oxide nanozyme is a composite formed by ZnIrOx clusters and ZnIrMOFs, named ZnIrOx / ZnIrMOFs, and the ZnIrOx / ZnIrMOFs nanozyme exhibits a nanosheet morphology, with the ZnIrOx clusters growing uniformly on the surface of the ZnIrMOFs, and the four elements C, O, Zn, and Ir being uniformly distributed within the ZnIrOx / ZnIrMOFs nanozyme.

[0008] Furthermore, the above ZnIrOx / ZnIrMOFs nanozyme has the multi-enzyme catalytic activity of oxidase-like enzymes and peroxidase-like enzymes, and the conditions under which the chemiluminescence detection platform based on the ZnIrOx / ZnIrMOFs nanozyme exhibits optimal sensing performance are a reaction temperature of 45°C, pH 11.0, a luminol concentration of 75 μM, and a ZnIrOx / ZnIrMOFs concentration of 1.5 μg / mL.

[0009] The present application further provides a method for preparing the metal oxide nanozyme entrapped in the above MOF, comprising the steps of:

[0010] In step S1, zinc acetate (ZnAc2) and iridium trichloride hydrate (IrCl3·3H2O) are dissolved in water, and Zn 2+ / Ir 3+ An aqueous solution is formed.

[0011] In step S2, 2,6-naphthalenedicarboxylic acid is dispersed in ethanol and subjected to ultrasonic treatment for 20 minutes to form a uniform dispersion, and the Zn obtained in step S1 is dissolved in the dispersion. 2+ / Ir 3+ Add to the aqueous solution.

[0012] In step S3, the mixture solution obtained in step S2 is transferred to a 20 mL glass reaction bottle and a solvothermal reaction is carried out.

[0013] In step S4, the solution after the reaction in step S3 is thoroughly washed three times with N'N-dimethylformamide (DMF) and ethanol, and then dried under vacuum at 60°C to obtain a product.

[0014] Furthermore, the mass ratio of the zinc acetate (ZnAc2) to iridium trichloride hydrate (IrCl3·3H2O) is 16:10.

[0015] Furthermore, the mass ratio of the iridium trichloride hydrate to 2,6-naphthalenedicarboxylic acid is 1:1.

[0016] Furthermore, the volume ratio of the water to the ethanol is 1:1.

[0017] Furthermore, the solvothermal reaction conditions in step S3 are a reaction temperature of 80° C. for 20 hours.

[0018] The present application further provides a method for detecting ascorbic acid on a chemiluminescence sensing platform constructed using the above MOF-confined metal oxide nanozymes.

[0019] Beneficial technical effects of the present application: (1) This application relates to the synthesis of 2,6-naphthalenedicarboxylic acid with Zn 2+ / Ir 3+ By reacting the ZnIrOx clusters with a mixed salt solution of ZnIrOx and utilizing the strong coordination interaction between the carboxyl-containing organic ligands and the metal ions, the size of the ZnIrOx clusters can be controlled during the formation of ZnIrMOFs, forming ZnIrOx cluster complexes confined in MOFs (ZnIrOx / ZnIrMOFs).

[0020] (2) This study successfully synthesized ZnIrOx / ZnIrMOFs with efficient oxidase-like and peroxidase-like multi-enzyme activities in the ethanol phase. The synthesis method is simple, environmentally friendly, and the conditions are relatively mild, with high yields.

[0021] (3) In this study, the confinement effect of MOF on IrOx during the synthesis process enables fine control of catalytic performance, thereby solving the problem of insufficient enzyme activity caused by the tendency of conventional micro-sized nanozymes to aggregate.

[0022] (4) The chemiluminescent sensing detection platform provided by the present application can achieve highly sensitive and specific detection of ascorbic acid by catalyzing the chemiluminescent reaction of oxidizing luminol with H2O2, and the operation is simple and rapid.

[0023] (5) This application provides a new design concept for the synthesis of high-performance nanozymes entrapped in MOFs and the construction of nanozyme sensors for rapid and simple detection of biomolecules such as ascorbic acid, further promoting research on controlling nanozyme performance by MOFs, enriching the variety of nanozymes, and broadening their applications in the field of chemiluminescence sensing. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a comparative diagram of the activity of Nanozyme at different metal salt ratios. [Figure 2] Scanning electron microscope image of the ZnIrOx / ZnIrMOFs with the best performance. [Figure 3] Transmission electron microscope image of the ZnIrOx / ZnIrMOFs with the best performance. [Figure 4] High-resolution transmission electron microscope image of the ZnIrOx / ZnIr MOFs with the best performance. [Figure 5] The HAADF-STEM image of the ZnIrOx / ZnIrMOFs with the best performance is shown. [Figure 6] EDX elemental surface scan analysis of ZnIrOx / ZnIrMOFs, where a is C element, b is O element, c is Zn element, and d is Ir element. [Figure 7] This is a comprehensive spectrum diagram of the X-ray photoelectron energy spectrum of ZnIrOx / ZnIrMOFs. [Figure 8] FIG. 1 is an X-ray photoelectron energy spectrum of Zn2p of ZnIrOx / ZnIrMOFs. [Figure 9] FIG. 1 is an X-ray photoelectron energy spectrum of Ir4f of ZnIrOx / ZnIrMOFs. [Figure 10] FIG. 1 is an X-ray photoelectron energy spectrum of O1s of ZnIrOx / ZnIrMOFs. [Figure 11] FIG. 1 is an X-ray photoelectron energy spectrum of C1s of ZnIrOx / ZnIrMOFs. [Figure 12] FIG. 1 shows the X-ray diffraction patterns of ZnMOF, IrOx / IrMOF and ZnIrOx / ZnIrMOFs. [Figure 13] FIG. 1 is a diagram verifying the activity of oxidase-like enzymes and peroxidase-like enzymes in ZnIrOx / ZnIrMOFs. [Figure 14] This is a diagram verifying the catalytic activity stability of ZnIrOx / ZnIrMOFs nanozyme for 20 days. [Figure 15] Figure 1 shows an experimental diagram of free radical scavenging in the ZnIrOx / ZnIrMOF / H2O2 system. [Figure 16] FIG. 1 shows the ultraviolet absorption spectrum of 1,3-diphenylisobenzofuran (DPBF) in the ZnIrOx / ZnIrMOF / H2O2 system. [Figure 17] Figure 1 shows the electron forward magnetic resonance spectra of 1O2 at different reaction times in the ZnIrOx / ZnIrMOF / H2O2 system. [Figure 18] Figure 1 shows the electron forward magnetic resonance spectra of OH· at different reaction times in the ZnIrOx / ZnIrMOFs / H2O2 system. [Figure 19] Figure 10 shows the electron forward magnetic resonance spectra of O2 ·- at different reaction times in the ZnIrOx / ZnIrMOF / H2O2 system. [Figure 20] FIG. 1 shows the Michaelis-Menten curves of ZnIrOx / ZnIrMOFs using TMB as a substrate. [Figure 21]Figure 1 shows the double reciprocal plot corresponding to the Michaelis-Menten curve of ZnIrOx / ZnIrMOFs with TMB as a substrate. [Figure 22] FIG. 1 shows the Michaelis-Menten curves of ZnIrOx / ZnIrMOFs using H2O2 as a substrate. [Figure 23] Figure 1 shows the double reciprocal plot corresponding to the Michaelis-Menten curve of ZnIrOx / ZnIr MOFs with H2O2 as the substrate. [Figure 24] FIG. 10 is a diagram schematically illustrating the influence of temperature on sensing performance. [Figure 25] FIG. 1 is a diagram schematically illustrating the effect of luminol concentration on sensing performance. [Figure 26] FIG. 1 is a diagram schematically illustrating the effect of pH on sensing performance. [Figure 27] FIG. 1 is a diagram schematically illustrating the effect of ZnIrOx / ZnIrMOFs concentration on sensing performance. [Figure 28] Figure 1 shows the principle of ascorbic acid detection by a chemiluminescence sensing platform based on ZnIrOx / ZnIrMOFs. [Figure 29] FIG. 1 shows the chemiluminescence kinetics curves of ascorbic acid detection at different concentrations. [Figure 30] FIG. 10 is a linear correlation diagram of ascorbic acid detection at different concentrations. [Figure 31] FIG. 1 is a diagram verifying selectivity for ascorbic acid detection. DETAILED DESCRIPTION OF THE INVENTION

[0025] In order to make the above objects, features and advantages of the present application more clearly understandable, the following detailed description of specific embodiments of the present application is not to be construed as a limitation on the applicable scope of the present application.

[0026] Example 1 16 mg of zinc acetate (ZnAc2) and 10 mg of IrCl3·3H2O were dissolved in 5 mL of water. 10 mg of 2,6-naphthalenedicarboxylic acid was dispersed in 5 mL of ethanol and sonicated for 20 minutes to form a uniform dispersion. 2+ / Ir 3+ After ultrasonic treatment for 2 minutes, the mixture was transferred to a 20 mL glass reaction bottle and kept at 80 °C for 20 hours. Finally, the mixture was thoroughly washed three times with N'N-dimethylformamide (DMF) and ethanol, respectively, and dried under vacuum at 60 °C to obtain the product.

[0027] Example 2 The only difference between Example 2 and Example 1 is that the mass ratio of (ZnAc2) to IrCl3·3H2O is 16 mg:12 mg, and the other conditions are exactly the same.

[0028] Example 3 The only difference between Example 3 and Example 1 is that the mass ratio of (ZnAc2) to IrCl3·3H2O is 16 mg:8 mg, and the other conditions are exactly the same.

[0029] Example 4 The only difference between Example 4 and Example 1 is that the mass ratio of (ZnAc2) to IrCl3·3H2O is 16 mg:5 mg, and the other conditions are exactly the same.

[0030] Example 5 The only difference between Example 5 and Example 1 is that the mass ratio of (ZnAc2) to IrCl3·3H2O is 16 mg:3 mg, and the other conditions are exactly the same.

[0031] Example 6 The only difference between Example 6 and Example 1 is that the mass ratio of (ZnAc2) to IrCl3·3H2O was 16 mg:0 mg, and the other conditions were exactly the same.

[0032] The catalytic performance of the products obtained in Examples 1 to 6 was investigated. Referring to FIG. 1, it can be seen that the catalytic performance of ZnIrOx / ZnIrMOFs was best at a ratio of 16 mg:10 mg.

[0033] Characterization of structural properties: The structural properties of the ZnIrOx / ZnIrMOFs nanozyme obtained in Example 1, which had the strongest enzymatic activity, were analyzed in detail using various characterization techniques, including scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction spectroscopy (XRD).

[0034] (1) SEM images (Figure 2) and HRTEM images (Figure 3) show that the ZnIrOx / ZnIrMOFs nanozyme exhibits a nanosheet morphology. HRTEM images reveal that relatively small ZnIrOx particles grow uniformly on the surface of the ZnIrMOFs (Figure 4). Furthermore, HAADF-STEM (Figure 5) and energy-dispersive X-ray elemental area scan analysis (Figure 6) of the nanozyme demonstrated the presence and uniform distribution of C, O, Zn, and Ir elements.

[0035] (2) Further analysis of the elemental composition of the ZnIrOx / ZnIrMOFs nanozyme using XPS revealed that the XPS spectrum of the ZnIrOx / ZnIrMOFs nanozyme exhibited four characteristic peaks: C1s, O1s, Zn2p, and Ir4f, indicating that the material consisted of four main components: C, O, Zn, and Ir (Figure 7). The high-resolution spectrum of Zn2p (Figure 8) revealed that the main peaks at 1022.36 eV and 1045.30 eV were Zn2p. 3 / 2 and Zn2p 1 / 2 It can be seen that it is attributed to electrons.

[0036] The Ir4f spectrum (Fig. 9) shows two main peaks at 64.55 eV and 61.56 eV corresponding to Ir-O and two satellite peaks. The O1s spectrum (Fig. 10) shows three peaks at 531.8 eV, 532.9 eV, and 533.8 eV corresponding to C=O, CO, and O-C=O. The C1s spectrum (Fig. 11) shows two peaks at 284.8 eV and 288.78 eV corresponding to C-C and O-C=O.

[0037] (3) The structures of ZnMOF, IrOx / IrMOFs, and ZnIrOx / ZnIrMOFs were characterized using XRD. As shown in Figure 12, the ZnIrOx / ZnIrMOFs exhibited characteristic peaks of both ZnMOF and IrOx / IrMOFs, indicating that the effective combination of the two was achieved through the confinement effect. The clear diffraction peaks indicated that the ZnIrOx / ZnIrMOFs nanozyme had good crystallinity.

[0038] The above various characterization means have proved the successful synthesis of ZnIrOx / ZnIrMOFs nanozymes.

[0039] 2. Verification of peroxidase and oxidase activity

[0040] The peroxidase-like activity of ZnIrOx / ZnIrMOFs was investigated through a color reaction with H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB). To do this, 400 μL of Britton-Robinson (BR) buffer (100 mM, pH 4.0), 30 μL of TMB (10 mM), and 40 μL of H2O2 (10 mM) were thoroughly mixed. Then, 30 μL of ZnIrOx / ZnIrMOFs (50 μg / mL) was added. After 5 minutes of incubation at room temperature, a blue color change was observed, with typical absorption at 652 nm.

[0041] The oxidase-like activity of ZnIrOx / ZnIrMOFs was studied through the color development caused by the direct oxidation of TMB by ZnIrOx / ZnIrMOFs, and the procedure was the same as that for the peroxidase-like activity, except that 40 μL of H2O2 was replaced with H2O.

[0042] As shown in Figure 13, neither pure TMB nor the mixture of H2O2 and TMB exhibited any absorption peaks, indicating a very slow reaction rate. In contrast, ZnIrOx / ZnIrMOFs themselves were able to undergo the TMB color reaction, exhibiting a corresponding characteristic peak at 652 nm. Furthermore, the presence of H2O2 significantly increased the absorption intensity of the ZnIrOx / ZnIrMOFs / TMB system. These results demonstrate that ZnIrOx / ZnIrMOFs possess excellent oxidase and peroxidase-like activity. Furthermore, the nanozyme maintained stable catalytic activity within 20 days (Figure 14), demonstrating the practical utility of the prepared ZnIrOx / ZnIrMOFs.

[0043] 3. Study on the catalytic mechanism of H2O2 / luminol system by ZnIrOx / ZnIrMOFs nanozyme

[0044] To elucidate the catalytic mechanism of ZnIrOx / ZnIrMOFs for chemiluminescence systems, free radical scavenging experiments and forward electron magnetic resonance spectroscopy studies were carried out. First, thiourea (Thi), histidine (His), and 1,4-benzoquinone (p-BQ) were scavenged with hydroxyl radicals (OH). · ), singlet oxygen ( 1 O2), superoxide anion (O2 ·- ) as a free radical scavenger, the active species in the system that may be involved in the reaction were analyzed. As shown in Figure 15, all of the different concentrations of Thi significantly suppressed the chemiluminescence signal, and the hydroxyl radical OH · is an important radical that catalyzes the reaction. High concentrations of His and p-BQ also slightly weakened the chemiluminescence signal, suggesting that singlet oxygen (1 O2) and superoxide anion (O2 · -) may be generated. 1,13-Diphenylisobenzofuran (DPBF) is a compound that can generate singlet oxygen ( 1 When ZnIrOx / ZnIrMOFs are irreversibly oxidized by H2O2, the absorption at 410 nm weakens. The reaction of ZnIrOx / ZnIrMOFs with H2O2 causes a decrease in the absorbance of DPBF, which is due to the presence of singlet oxygen ( 1 Further evidence for the formation of singlet oxygen (O2) was obtained (Figure 16). 1 2,3-Dimethylpyridine N-oxide (DMPO) is used as a spin trap for hydroxyl radicals (OH · ) and singlet oxygen ( 1 O2) as a scavenger, and the presence of these free radicals was confirmed through EPR results. As the reaction time of ZnIrOx / ZnIrMOFs with H2O2 increased, the amount of singlet oxygen ( 1 O2) (Figure 17), hydroxyl radical (OH · ) (Figure 18), and superoxide anion (O ·- ) (Figure 19) were observed, and the peaks became increasingly stronger. All three of the above radicals were generated during the catalysis of H2O2 decomposition by ZnIrOx / ZnIrMOFs, and were proven to be key species in the oxidation of luminol.

[0045] 4. Evaluation of catalyst performance

[0046] Steady-state kinetic measurements are performed on the system by recording absorbance at 652 nm within a selected time interval (100 measurements and a dynamic interval of 1 second) in a dynamic cycle model. Kinetic data are calculated using the Lineweaver-Burk equation.

[0047] JPEG2026031397000002.jpg647

[0048] where v, V max , [S] and Km represent the initial color reaction rate, the maximum reaction rate, the substrate (TMB or H2O2) concentration, and the Michaelis constant, respectively.

[0049] The peroxidase-like activity of ZnIrOx / ZnIrMOFs was quantitatively evaluated and compared by calculating parameters such as Km and Vmax using double reciprocal plots of the initial reaction rates. m A smaller value indicates a stronger affinity of the enzyme for the corresponding substrate. As shown in Figures 20 to 23, the Km values ​​of ZnIrOx / ZnIrMOFs for TMB and H2O2 were 0.232 mM and 1.31 mM, respectively, indicating good binding affinity of ZnIrOx / ZnIrMOFs for the substrates.

[0050] Example 7 Optimization of the sensing performance of the chemiluminescence detection platform based on ZnIrOx / ZnIrMOFs nanozyme

[0051] To achieve optimal sensing performance for ascorbic acid, the controlled variable method was used to optimize parameters such as temperature, pH, and catalyst concentration, as well as luminol concentration, which affect the catalytic activity of the ZnIrOx / ZnIrMOFs nanozyme. The specific procedure is as follows. First, the reaction temperature was varied (room temperature, 30°C, 35°C, 40°C, 45°C, 50°C, and 55°C, Figure 24) without changing other reaction conditions, and the optimal reaction temperature was determined to be 45°C. At 45°C, only the luminol concentration was varied (10 μM, 17.5 μM, 25 μM, 40 μM, 50 μM, 75 μM, 100 μM, 150 μM, and 200 μM, Figure 25). The optimal luminol concentration was determined to be 75 μM. Furthermore, the pH (Figure 26) and the ZnIrOx / ZnIrMOFs concentration (Figure 27) were sequentially optimized, and finally, the optimal reaction conditions were determined to be a reaction temperature of 45°C, pH 11.0, a luminol concentration of 75 μM, and a ZnIrOx / ZnIrMOFs concentration of 1.5 μg / mL.

[0052] Example 8 Detection of ascorbic acid by a chemiluminescence sensing platform based on MOF-confined ZnIrOx / ZnIrMOFs nanozymes

[0053] (1) In the chemiluminescence process of luminol catalyzed by ZnIrOx / ZnIrMOFs, oxidized luminol and several reactive oxygen species are produced. AA has excellent reducing properties and can reduce oxidized luminol and some reactive oxygen species. It also acts as a free radical scavenger, eliminating some hydroxyl radicals and quenching the chemiluminescence signal. The higher the AA content, the smaller the chemiluminescence signal, allowing for quantitative detection of AA (Figure 28).

[0054] Ascorbic acid (AA) standard solutions were analyzed under the optimized conditions described above (Figure 29). A 100 μL mixture of ZnIrOx / ZnIrMOFs and luminol was prepared, with a final concentration of 6 μg / mL for ZnIrOx / ZnIrMOFs and a final concentration of 300 μM for luminol, using water as the solvent. After uniformly mixing 250 μL of the mixture with equal volumes of AA at different concentrations, 100 μL of the mixture was added to a white ELISA plate well. An autosampler was used to inject 100 μL of HO solution (20 mM, pH 11, dissolved in 100 mM BR buffer) into the well plate. Simultaneously, the chemiluminescence kinetics curve was recorded using an ELISA plate reader, with the photomultiplier tube voltage set to 2000 V. It can be seen that the ascorbic acid concentration and chemiluminescence intensity show a good linear relationship in the range of 0.20 μM to 2.60 μM, with a detection limit of 0.13 μM (Figure 30). Furthermore, this sensing platform exhibits excellent selectivity for the detection of ascorbic acid. Figure 31 shows that only AA can cause a clear decrease in the chemiluminescence signal, while the influence of several other interfering substances is not significant. This indicates that the developed sensing strategy has good practical potential for the detection of ascorbic acid.

Claims

1. A metal oxide nanozyme confined in a MOF, the metal oxide nanozyme being a composite formed by ZnIrOx clusters and ZnIrMOFs, named ZnIrOx / ZnIrMOFs, the ZnIrOx / ZnIrMOFs nanozyme exhibiting a nanosheet morphology, the ZnIrOx clusters growing uniformly on the surface of the ZnIrMOFs, and the four elements C, O, Zn, and Ir being uniformly distributed within the ZnIrOx / ZnIrMOFs nanozyme; The method for producing the metal oxide nanozyme confined in the MOF comprises: Zinc acetate ZnAc 2 and iridium trichloride hydrate IrCl 3 ・3H 2 O and dissolved in water, and Zn 2+ / Ir 3+ Step S1 of forming an aqueous solution; 2,6-Naphthalenedicarboxylic acid was dispersed in ethanol and subjected to ultrasonic treatment for 20 minutes to form a uniform dispersion. 2+ / Ir 3+ Step S2 of adding to an aqueous solution; Step S3: transferring the mixture solution obtained in step S2 into a 20 mL glass reaction bottle and carrying out a solvothermal reaction; and step S4, in which the solution after the reaction in step S3 is thoroughly washed three times with N'N-dimethylformamide and ethanol, and dried in vacuum at 60°C to obtain a product.

2. The ZnIrOx / ZnIr MOFs nanozyme has multi-enzyme catalytic activity of oxidase-like enzymes and peroxidase-like enzymes, and the optimal sensing performance of the chemiluminescence detection platform based on the ZnIrOx / ZnIr MOFs nanozyme is achieved under the following conditions: a reaction temperature of 45°C, a pH of 11.0, a luminol concentration of 75 μM, and a concentration of the ZnIrOx / ZnIr MOFs of 1.5 μg / mL.

3. 2. The MOF-confined metal oxide nanozyme of claim 1, wherein the mass ratio of zinc acetate to iridium trichloride hydrate is from 16:12 to 16:

3.

4. 2. The MOF-confined metal oxide nanozyme according to claim 1, wherein the mass ratio of the iridium trichloride hydrate to 2,6-naphthalenedicarboxylic acid is 1:

1.

5. 2. The MOF-confined metal oxide nanozyme of claim 1, wherein the volume ratio of water to ethanol is 1:

1.

6. The metal oxide nanozyme confined in MOF according to claim 1, characterized in that the solvothermal reaction conditions in step S3 are 80°C and 20 hours.

7. A method for detecting ascorbic acid, characterized by using a metal oxide nanozyme confined in the MOF according to claim 1 or 2.

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