A nanozyme for detecting heavy metals, its preparation method and application

Abstract

The present invention relates to a nanozyme for detecting heavy metals, a preparation method and an application thereof, which is an organic-inorganic composite material formed by in-situ loading of copper-doped cerium oxide on the surface of NH 2 -MIL-101(Fe). The nanozyme has a simple structure and a simple synthesis process, and has the advantages of visible to the naked eye, simplicity and convenience in detecting Hg(II). By utilizing the advantages of high specific surface area and high porosity of NH 2 -MIL-101(Fe), copper-doped cerium oxide is loaded onto the surface so that the copper-doped cerium oxide can be better dispersed, increasing the active sites. The nanozyme has good detection ability for mercury ions, with a wide linear range, a low detection limit and good specificity.

Description

Technical Field

[0001] The invention relates to a nanozyme for detecting heavy metals and a preparation method and application thereof, and belongs to the field of heavy metal detection. Background Art

[0002] Today, environmental pollution remains one of the most important problems facing mankind. With the continuous development of industrial production and manufacturing, heavy metal pollution is becoming more and more serious. Wastewater containing heavy metal ions discharged into the environment will pollute soil and water sources, thereby affecting crops, animals and plants, and eventually accumulate in the human body, causing serious diseases. For example, exposure to mercury ions Hg(Ⅱ) through drinking contaminated drinking water and food may cause some serious diseases, such as bronchitis, pneumonia and other diseases. Therefore, it is particularly important to develop effective heavy metal detection methods.

[0003] Commonly used methods for detecting heavy metals include electrochemical method, inductively coupled plasma mass spectrometry, ion chromatography, atomic absorption spectrometry, colorimetry and fluorescence spectrometry, etc. Among these attractive detection methods, colorimetry has the advantages of fast detection, visibility to the naked eye, and convenient operation in addition to high selectivity and sensitivity. It has been widely used in the development of portable instant detection equipment. It uses the catalytic action of enzymes to change the color of the chromogenic substrate and is one of the commonly used colorimetric methods.

[0004] Natural enzymes have many shortcomings, such as poor stability, high preparation, purification and storage costs, etc. These shortcomings greatly affect the activity and application of natural enzymes. In order to avoid the defects of natural enzymes, nanozymes, as an artificial enzyme, came into being. They have the advantages of low cost, high stability, simple preparation, and mass production, and have received more and more attention. It has gradually become a very popular material in the fields of biology, medicine, industry, food and environment. With the rapid progress and development of modern nanomaterial technology and biotechnology, the development of nanozymes has also been greatly promoted. At present, many artificial enzymes have been proven to be able to simulate many different enzyme activities.

[0005] There are currently a small number of reports on nanozymes for detecting heavy metals, but they all have the disadvantages of narrow detection range, high detection limit and poor specificity. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a nanozyme for detecting heavy metals and a preparation method and application thereof. The nanozyme of the present invention has four enzyme activities, a wide linear range for detecting Hg(II), a low detection limit and good specificity.

[0007] In order to achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0008] A nanozyme for detecting heavy metals, copper-doped cerium oxide is loaded onto NH2 -Organic-inorganic composite material formed on the surface of MIL-101(Fe).

[0009] The preparation method of the above-mentioned nanozyme for detecting heavy metals comprises the following steps:

[0010] (1) Provide NH 2 -MIL-101(Fe);

[0011] (2) Put Ce(NO 3 ) 3 6H 2 O, Cu(NO 3 ) 2 ·3H 2 O, dissolved in deionized water, then the precipitant was added dropwise to the solution, heated and stirred for 20-40 min, the precipitated slurry was aged, centrifuged, washed with hot deionized water until the pH of the upper solution was 7, vacuum dried, and calcined to obtain Cu / CeO 2 powder;

[0012] (3) NH 2 -MIL-101(Fe) and Cu / CeO 2 The powder was dispersed in deionized water, mechanically stirred for 15-25h, centrifuged to collect the precipitate, and vacuum dried to obtain the nanozyme NH 2 -MIL-101(Fe)@Cu / CeO 2 .

[0013] According to the preferred embodiment of the present invention, in step (1), NH 2 -MIL-101(Fe) is prepared as follows:

[0014] BDC-NH 2 Dissolve in DMF and then add FeCl 3 6H 2 The mixture of O and DMF was stirred at room temperature for 1 hour, and the resulting mixture was transferred to a polytetrafluoroethylene autoclave and kept at 110-120°C for 15-25 hours. After cooling to room temperature, the product was centrifuged, washed with DMF and methanol, and dried in vacuo to obtain NH 2 -MIL-101(Fe).

[0015] Further preferably, BDC-NH 2 The mass volume ratio with DMF is (0.3-0.5): 15, unit, g / mL, FeCl 3 6H 2 FeCl in a mixture of O and DMF 3 6H 2The mass volume ratio of O to DMF is (1-3): 15, unit, g / mL, BDC-NH 2 With FeCl 3 6H 2 The mass ratio of O is (0.3-0.5):(1-3).

[0016] More preferably, the vacuum drying time is 20-24 hours.

[0017] According to the preferred embodiment of the present invention, in step (2), Ce(NO 3 ) 3 6H 2 O and Cu(NO 3 ) 2 ·3H 2 The mass ratio of O is 1:(0.05-0.1), Ce(NO 3 ) 3 6H 2 The mass volume ratio of O to deionized water is 1:(100-150), unit, g / mL.

[0018] Preferably, according to the present invention, in step (2), the precipitant is 0.4-0.6 mol / L KOH, and the amount of the precipitant added is such that the pH of the system reaches 9-11.

[0019] Preferably, according to the present invention, in step (2), the heating and stirring temperature is 65-80° C., the slurry aging time is 1-3 h, and the vacuum drying time is 12 h.

[0020] Preferably according to the present invention, in step (2), the calcination is carried out in the atmosphere at a heating rate of 4-6°C / min to 400-600°C for 4-6 hours.

[0021] According to the preferred embodiment of the present invention, in step (3), NH 2 -MIL-101(Fe) and Cu / CeO 2 The mass ratio of the powder is (3-8):1.

[0022] According to the preferred embodiment of the present invention, in step (3), NH 2 -The mass ratio of MIL-101(Fe) to deionized water is 1:(10-15).

[0023] The above-mentioned application of the nanozyme for detecting heavy metals is used to detect Hg(Ⅱ) heavy metals.

[0024] According to the preferred embodiment of the present invention, the specific detection method is as follows:

[0025] 1) Add different concentrations of Hg(Ⅱ) standard solution and different concentrations of glutathione (GSH) solution into the buffer solution and react at room temperature for 5-20 minutes to allow Hg(Ⅱ) and glutathione (GSH) to react fully. Then add 3,3',5,5'-tetramethylbenzidine TMB solution and H 2 O 2 NH 2 -MIL-101(Fe)@Cu / CeO 2 For aqueous dispersions, the concentration-absorbance curve was obtained by recording the absorbance of the detection system at 652 nm;

[0026] 2) Add the sample to be tested and glutathione (GSH) into the buffer solution, measure the absorbance at 652 nm according to the method in step 1), and obtain the concentration of Hg(II) in the sample to be tested through the concentration-absorbance curve.

[0027] Preferably according to the present invention, in step 1), the buffer is a NaAc / HAc buffer with a pH of 3 to 5.

[0028] Further preferably, in step 1), the buffer is a NaAc / HAc buffer with a pH of 4.

[0029] Preferably according to the present invention, in step 1), the concentration of the glutathione solution is 20-40 μM, and most preferably, the concentration of the glutathione solution is 30 μM.

[0030] According to the present invention, preferably, in step 1), the volume ratio of the Hg(II) standard solution to the buffer solution is 1:(4-8), and the volume ratio of the glutathione (GSH) solution to the buffer solution is 1:(4-8).

[0031] According to the present invention, preferably, in step 1), the concentration of TMB solution is 0.2-0.4 mM, H 2 O 2 The concentration of NH 2 -MIL-101(Fe)@Cu / CeO 2 The concentration of the aqueous dispersion is 0.2-0.4 mg / mL.

[0032] According to the present invention, preferably, in step 1), TMB solution, H 2 O 2 NH 2 -MIL-101(Fe)@Cu / CeO 2 The volume ratio of the aqueous dispersion is 1:1:1.

[0033] According to the present invention, preferably, in step 1), the buffer and NH 2 -MIL-101(Fe)@Cu / CeO2 The volume ratio of the aqueous dispersion is (2-6):1.

[0034] Compared with the prior art, the advantages and positive effects of the present invention are:

[0035] 1. NH prepared by the present invention 2 -MIL-101(Fe)@Cu / CeO 2 The composite nanomaterial has four enzyme properties. In the presence of hydrogen peroxide, NH 2 -MIL-101(Fe)@Cu / CeO 2 Nanozymes can oxidize TMB to blue ox-TMB. When glutathione is added to the system, ox-TMB can be reduced, and the system turns from blue to colorless. When Hg(Ⅱ) and glutathione are added to the system at the same time, Hg(Ⅱ) will bind to the sulfhydryl group of glutathione, reducing the degree of fading of the system, thereby quantitatively detecting Hg(Ⅱ). After optimizing the glutathione concentration (30μM), a calibration curve of absorbance and mercury ion concentration was obtained by adding different concentrations of Hg(Ⅱ). Thus, Hg(Ⅱ) can be sensitively detected.

[0036] 2. The composite nanozyme of the present invention has the advantages of being visible to the naked eye and easy to detect for Hg(II).

[0037] 3. The composite nanozyme has a relatively wide detection range (0.1-50 μM) and a low detection limit of 0.1 μM for detecting Hg(Ⅱ). BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The nanozyme NH prepared in Example 1 2 -MIL-101(Fe)@Cu / CeO 2 SEM image of .

[0039] Figure 2 NH obtained in step (1) of Example 1 2 -MIL-101(Fe), Cu / CeO obtained in step (2) 2 NH obtained in step (3) 2 -MIL-101(Fe)@Cu / CeO 2 XRD pattern of .

[0040] Figure 3 The linear relationship for detecting Hg(Ⅱ) DETAILED DESCRIPTION

[0041] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[0043] The experimental methods described in the following examples are conventional methods unless otherwise specified.

[0044] The kinetic parameters of the composite nanozyme are fitted by the following equation:

[0045] V 0 =V max [S] / (K m +[S])(Formula 1)

[0046] Among them, K m represents the Michaelis constant, and [S] represents the substrate concentration. V 0 represents the initial reaction rate, V max Represents the maximum reaction speed.

[0047] Unless otherwise specified, the reagents and materials used in the following examples can be obtained from commercial sources.

[0048] Example 1

[0049] Nanozyme NH 2 -MIL-101(Fe)@Cu / CeO 2 Synthesis of:

[0050] 1) 0.45 g BDC-NH 2 (2.5 mmol) was dissolved in 15 ml of DMF, and then 1.35 g of FeCl 3 6H 2 A mixture of O (5.0 mmol) and 15 mL of DMF was added to the above solution. After stirring at room temperature for 1 hour, the resulting mixture was transferred to a 50 mL polytetrafluoroethylene-lined autoclave and placed in an oven at 115 °C for 20 hours. After cooling to room temperature, the powder product was centrifuged, washed several times with DMF and methanol, and finally dried under vacuum for 24 hours to obtain NH 2 -MIL-101(Fe);

[0051] 2) 1g Ce(NO 3 ) 3 6H 2O, 0.087 g Cu(NO 3 ) 2 ·3H 2 O, dissolved in 100 ml of deionized water, metal ion coprecipitation, then the precipitant 0.5M KOH was added dropwise to the above solution, the pH reached 10 at 70 ° C, stirred for 30 minutes, the precipitated slurry was aged for 2 hours, the newly precipitated slurry was centrifuged and washed several times with hot deionized water until the pH of the upper solution reached about 7, and finally dried under vacuum for 12 hours, and then heated to 500 ° C at a heating rate of 5 ° C / min in the atmosphere, calcined for 5 hours, and Cu / CeO 2 ;

[0052] 3) NH 2 -MIL-101(Fe) and Cu / CeO 2 Dispersed in deionized water, NH 2 -MIL-101(Fe) and Cu / CeO 2 The mass ratio of the powder is 4:1, NH 2 -MIL-101(Fe) and deionized water in a mass ratio of 1:12, mechanically stirred for 20 h, centrifuged to collect the precipitate, and then dried under vacuum for 12 h. 2 -MIL-101(Fe)@Cu / CeO 2 .

[0053] The material synthesized in Example 1 was characterized. Figure 1 For NH 2 -MIL-101(Fe)@Cu / CeO 2 SEM images of Figure 2 is the NH obtained in step (1) 2 -MIL-101(Fe), Cu / CeO obtained in step (2) 2 NH obtained in step (3) 2 -MIL-101(Fe)@Cu / CeO 2 The XRD pattern shows that copper-doped cerium oxide was successfully loaded onto NH 2 -MIL-101(Fe).

[0054] Experimental Example 1

[0055] NH 2 -MIL-101(Fe)@Cu / CeO 2 Evaluation of the performance of peroxidase-like

[0056] The nanozyme NH prepared in Example 1 2 -MIL-101(Fe)@Cu / CeO 2Add water to prepare a dispersion, add the dispersion (200 μL, 0.25 mg / mL) to NaAc / HAc buffer (1.2 mL) with a pH of 2 to 11, and then add H 2 O 2 (200 μL, 15 mM), TMB (200 μL, 0.3 mM), react at room temperature for 5 min, measure the absorbance of the mixed solution at 652 nm using an ultraviolet-visible spectrophotometer (UV-vis), and obtain the relative activity of peroxidase-like enzymes at different pH values ​​(see Table 1).

[0057] Table 1 NH 2 -MIL-101(Fe)@Cu / CeO 2 The relative activity of peroxidase-like enzymes.

[0058] pH 2 3 4 5 7 8 9 11 13 Relative activity 36％ 52％ 100％ 51％ 48％ 40％ 23％ 20％ 18％

[0059] It can be seen from Table 1 that when the pH is 4, the performance of the peroxidase-like enzyme is optimal. Under the optimal conditions, it is calculated by formula 1 that NH 2 -MIL-101(Fe)@Cu / CeO 2 K of peroxidase-like enzymes for TMB m 0.02mM,V max is 3.82×10 -5 mM / s, for H 2 O 2 K m 0.49mM, V max 5.76×10 -4 mM / s.

[0060] Experimental Example 2

[0061] Detection of Hg(Ⅱ)

[0062] (1) preparing a NaAc / HAc buffer solution with a pH of 4;

[0063] (2) Add different concentrations of Hg(Ⅱ) solution and 30 μM glutathione (GSH) solution to the buffer solution of step (1), the volume ratio of Hg(Ⅱ) standard solution to buffer solution is 1:5, and the volume ratio of glutathione (GSH) solution to buffer solution is 1:5. The mixture is reacted at room temperature for 10 minutes to allow Hg(Ⅱ) and glutathione (GSH) to react fully. Then, TMB solution (200 μL, 0.3 mM) and H 2 O 2 (200 μL, 15 mM) and NH 2 -MIL-101(Fe)@Cu / CeO 2(200 μL, 0.25 mg / mL) aqueous dispersion, by recording the absorbance of the detection system at 652 nm, a series of concentration-absorbance curves were obtained. The linear relationship is as follows Figure 3 shown.

[0064] Experimental Example 3 Specificity

[0065] (1) preparing a NaAc / HAc buffer solution with a pH of 4;

[0066] (2) Mn 2+ ,Co 2+ ,Ni 2+ ,Zn 2+ ,Pb 2+ ,Cd 2+ ,Na + ,Fe 3+ Different heavy metal ion solutions and 30 μM glutathione (GSH) solution were added to the buffer solution in step (1), the volume ratio of Hg (II) standard solution to buffer solution was 1:5, and the volume ratio of glutathione (GSH) solution to buffer solution was 1:5. The mixture was reacted at room temperature for 10 minutes to allow the metal ions and glutathione (GSH) to react fully. TMB (200 μL, 0.3 mM), H 2 O 2 (200 μL, 15 mM) and NH 2 -MIL-101(Fe)@Cu / CeO 2 (200μL, 0.25mg / mL) suspension. By recording the absorbance of the detection system at 652nm, it was found that only after Hg(Ⅱ) was added, the absorbance of the system had a significant difference from that of the blank control. The addition of other metal ions would not restore the absorbance of the system, indicating that the monitoring system has good selectivity for Hg(Ⅱ). The results are shown in Table 2.

[0067] Table 2 Absorbance of different heavy metal ions in the monitoring system

[0068]

[0069]

[0070] Experimental Example 4

[0071] Analysis of Hg(Ⅱ) concentration in tap water samples

[0072] To verify the NH 2 -MIL-101(Fe)@Cu / CeO 2To demonstrate the practicality of the nanozyme detection system, we applied this detection method to detect the concentration of Hg(Ⅱ) in tap water samples. Tap water samples were collected from laboratory water sources. 2 mL of the actual treated water sample was diluted with NaAC / HAc buffer solution (2 mL, pH 4). 200 μL of the diluted water sample and GSH (200 μL, 30 μM) were added to NaAC / HAc buffer solution (1.2 mL, pH 4) and reacted for 10 minutes to allow glutathione to fully react with Hg(Ⅱ), followed by the addition of NH 2 -MIL-101(Fe)@Cu / CeO 2 (200 μL, 0.25 mg / mL) suspension, TMB (200 μL, 0.3 mM), H 2 O 2 (200 μL, 15 mM), and then the reaction system was measured using a UV-visible spectrophotometer to obtain A 652nm In order to calculate the relative standard deviation (RSD), GSH (200 μL, 30 μM), (200 μL, 5, 10, 50 μM) Hg (Ⅱ), NH 2 -MIL-101(Fe)@Cu / CeO 2 (200 μL, 0.25 mg / mL) suspension, TMB (200 μL, 0.3 mM), H 2 O 2 (200 μL, 15 mM) were mixed, and the reaction system was measured by UV-visible spectrophotometer to obtain A 652nm The recovery rate was calculated by the following formula and the test results are shown in Table 3.

[0073] Recovery rate = [(measured value of spiked sample - measured value of sample) / spiked amount] × 100% (Formula 2)

[0074] Table 3 Detection of Hg(Ⅱ) in actual tap water samples

[0075]

[0076] Experimental Example 5

[0077] Analysis of Hg(Ⅱ) concentration in sewage samples

[0078] The sewage sample was treated with a filter membrane with a pore size of 0.2 μm to remove impurities such as weeds and soil. First, 2 mL of the actual treated water sample was diluted with NaAc / HAc buffer solution (2 mL, pH 4). 200 μL of the diluted water sample and GSH (200 μL, 30 μM) were added to NaAc / HAc buffer solution (1.2 mL, pH 4) and reacted for 10 minutes to allow glutathione to fully react with Hg (II), and then NH 2-MIL-101(Fe)@Cu / CeO 2 (200 μL, 0.25 mg / mL) suspension, TMB (200 μL, 0.3 mM), H 2 O 2 (200 μL, 15 mM), and then the reaction system was measured using a UV-visible spectrophotometer to obtain A 652nm In order to calculate the relative standard deviation (RSD), GSH (200 μL, 30 μM), (200 μL, 5, 10, 50 μM) Hg (Ⅱ), NH 2 -MIL-101(Fe)@Cu / CeO 2 (200 μL, 0.25 mg / mL) suspension, TMB (200 μL, 0.3 mM), H 2 O 2 (200 μL, 15 mM) were mixed, and the reaction system was measured by UV-visible spectrophotometer to obtain A 652nm The recovery rate is calculated by formula 2, and the test results are shown in Table 4.

[0079] Table 4 Detection of Hg(Ⅱ) in actual sewage samples

[0080]

[0081] The average recovery rates of tap water samples and sewage samples were 99.2% to 101.1%, and the relative standard deviation was less than 3.57%.

[0082] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A nanozyme for detecting heavy metals, copper-doped cerium oxide in situ loaded on NH 2 - Organic-inorganic composite material formed on the surface of MIL-101 (Fe); It is prepared by the following method: (1) Providing NH 2 -MIL-101(Fe); (2) Change Ce(NO 3 ) 3 6H 2 O、Cu(NO 3 ) 2 ·3H 2 O, dissolved in deionized water, then the precipitant was added dropwise to the solution, heated and stirred for 20-40 min, the precipitated slurry was aged, centrifuged, washed with hot deionized water until the pH of the upper solution was 7, vacuum dried, and calcined to obtain Cu / CeO 2 powder; (3) NH 2 -MIL-101(Fe) and Cu / CeO 2 The powder was dispersed in deionized water, mechanically stirred for 15-25h, centrifuged to collect the precipitate, and vacuum dried to obtain the nanozyme NH 2 -MIL-101(Fe)@Cu / CeO 2 .

2. The nanozyme for detecting heavy metals according to claim 1, It is characterized in that In step (1), NH 2 -MIL-101(Fe) is prepared as follows: BDC-NH 2 Dissolve in DMF and then add FeCl 3 ⋅6H 2 The mixture of O and DMF was stirred at room temperature for 1 hour, and the resulting mixture was transferred to a polytetrafluoroethylene autoclave and kept at 110-120°C for 15-25 hours. After cooling to room temperature, the product was centrifuged, washed with DMF and methanol, and dried in vacuo to obtain NH 2 -MIL-101(Fe); BDC-NH 2 The mass volume ratio with DMF is (0.3-0.5): 15, unit, g / mL, FeCl 3 ⋅6H 2 FeCl in a mixture of O and DMF 3 ⋅6H 2 The mass volume ratio of O to DMF is (1-3): 15, unit, g / mL, BDC-NH 2 With FeCl 3 ⋅6H 2 The mass ratio of O is (0.3-0.5):(1-3); The vacuum drying time is 20-24 hours.

3. The nanozyme for detecting heavy metals according to claim 1, It is characterized in that In step (2), Ce(NO 3 ) 3 6H 2 O and Cu(NO 3 ) 2 ·3H 2 The mass ratio of O is 1: (0.05-0.1), Ce(NO 3 ) 3 6H 2 The mass volume ratio of O to deionized water is 1:(100-150), unit, g / mL.

4. The nanozyme for detecting heavy metals according to claim 1, It is characterized in that In step (2), the precipitant is 0.4-0.6 mol / L KOH, the amount of precipitant added is such that the pH value of the system reaches 9-11, the heating and stirring temperature is 65-80°C, the slurry aging time is 1-3h, the vacuum drying time is 12h, and the calcination is carried out in the atmosphere at a heating rate of 4-6°C / min to 400-600°C for 4-6 hours.

5. The nanozyme for detecting heavy metals according to claim 1, It is characterized in that In step (3), NH 2 -MIL-101(Fe) and Cu / CeO 2 The mass ratio of powder is (3-8):

1.

6. The nanozyme for detecting heavy metals according to claim 1, It is characterized in that NH 2 -The mass ratio of MIL-101(Fe) to deionized water is 1:(10-15).

7. The use of the nanozyme for detecting heavy metals according to claim 1, for detecting Hg(II) heavy metals; The specific detection methods are as follows: 1) Add different concentrations of Hg(Ⅱ) standard solution and different concentrations of glutathione (GSH) solution into the buffer solution and react at room temperature for 5-20 minutes to allow Hg(Ⅱ) and glutathione (GSH) to react fully. Then add 3,3',5,5'-tetramethylbenzidine TMB solution and H 2 O 2 NH 2 -MIL-101(Fe)@Cu / CeO 2 For aqueous dispersions, the concentration-absorbance curve was obtained by recording the absorbance of the detection system at 652 nm; 2) Add the sample to be tested and glutathione (GSH) to the buffer solution, test the absorbance at 652 nm according to the method in step 1), and obtain the concentration of Hg(Ⅱ) in the sample to be tested through the concentration-absorbance curve.

8. The use according to claim 7, It is characterized in that In step 1), the buffer is a NaAc / HAc buffer with a pH of 3 to 5. The concentration of glutathione solution is 20-40µM; The volume ratio of Hg(Ⅱ) standard solution to buffer solution was 1:(4-8), and the volume ratio of glutathione (GSH) solution to buffer solution was 1:(4-8).

9. The use according to claim 7, It is characterized in that In step 1), the concentration of TMB solution is 0.2-0.4 mM, H 2 O 2 The concentration of NH 2 -MIL-101(Fe)@Cu / CeO 2 The concentration of the aqueous dispersion is 0.2-0.4 mg / mL; TMB solution, H 2 O 2 NH 2 -MIL-101(Fe)@Cu / CeO 2 The volume ratio of the aqueous dispersion is 1:1:1; Buffer and NH 2 -MIL-101(Fe)@Cu / CeO 2 The volume ratio of the aqueous dispersion is (2-6):1.

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