Colorimetric-luminous dual-mode probe capable of being used for copper ion detection as well as preparation method and application of colorimetric-luminous dual-mode probe

Abstract

The invention belongs to the technical field of analysis and detection, and discloses a colorimetric-luminescence dual-mode probe for copper ion detection. According to the fluorescent probe, lanthanide metals Tb, Eu, Dy, Sm, Pr, Ho, Er and the like are used as central metals, benzenetricarboxylic acid, isophthalic acid and 2-aminoterephthalic acid are used as ligands to be coordinated and combined with lanthanide ions, and a lanthanide coordination polymer is formed. The luminescence change of the green fluorescence of the Tb-MOFs-coated PEI in a copper ion solution is taken as a reference by the probe, when the color of the solution is obviously changed after the copper ions are added, the luminescence intensity of the Tb-MOFs-coated PEI-Cu < 2 + > can be reduced due to the concentration quenching effect. According to the change of the color of the copper ions and the change of the luminous intensity of the Tb-MOFs (at) PEI, the rapid, sensitive and specific detection of the copper ions is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of analysis and detection, and particularly relates to a colorimetric-luminescent dual-mode probe that can be used for copper ion detection. Background Art

[0002] Copper ions play a vital role in life systems. As a trace element, they are widely distributed in various biological tissues. The presence of copper ions is essential for maintaining the normal physiological functions of organisms. Copper ions play a bridging role in redox reactions in organisms. They can accept electrons and transfer them to other molecules, thereby promoting redox reactions. Secondly, copper ions also play an important role in the structure and function of proteins, in maintaining the stability and strength of connective tissues, in nerve conduction, and in the immune system. However, excessive copper ions may also cause harm to organisms. Copper ions have certain toxicity, and excessive intake may cause oxidative stress and cell damage. There is a fine regulatory mechanism in the copper ion organism to ensure that the concentration of copper ions is maintained at an appropriate level. Therefore, it is of great significance to develop methods that can be used to accurately detect copper ions in water, the environment, and organisms.

[0003] At present, the detection methods of copper ions are mainly divided into two categories: direct method and indirect method. The direct method is a method of direct analysis and detection using the physical and chemical properties of copper ions themselves, including atomic absorption spectroscopy, emission spectroscopy and ion selective electrode method. The indirect method analyzes and detects copper ions through the signal changes produced by the specific chemical reaction or supramolecular action between copper ions and indicators (also called chemical molecular probes). The colorimetric-fluorescence dual-mode sensing technology combines the advantages of high sensitivity of fluorescence technology and naked-eye visualization of chemical colorimetric technology and is portable, making it one of the most promising methods in the field of copper ion detection. Therefore, it is very meaningful to develop colorimetric-fluorescence dual-mode probe molecules with fast response, high sensitivity and good selectivity. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that traditional fluorescence methods are easily affected by environmental interference and inaccurate detection, and to provide a colorimetric-luminescent dual-mode probe for detecting copper ions, which can achieve high-sensitivity, high-precision, simple and rapid detection of target copper ions. The operation process is simple, the cost is low, and the detection results have good reproducibility.

[0005] To achieve the above purpose, a colorimetric-luminescent dual-mode probe that can be used for copper ion detection is prepared by using rare earth elements as the luminescent center and ligand-coated PEI composite.

[0006] The above-mentioned colorimetric-luminescent dual-mode probe can be used for copper ion detection, and the rare earth element is one of Tb, Eu, Dy, Sm, Pr, Ho, and Er ions.

[0007] The above-mentioned colorimetric-luminescent dual-mode probe can be used for copper ion detection, and the ligand is one of trimesic acid, isophthalic acid, and 2-aminoterephthalic acid.

[0008] The preparation method of the above-mentioned colorimetric-luminescent dual-mode probe that can be used for copper ion detection comprises the following steps:

[0009] 1) dissolving Ln(NO3)3, Y(NO3)3 and sodium acetate in deionized water, adding ligand and DMF solution to obtain a white solution by ultrasonication, adding the white solution to a reactor for reaction, then cooling to room temperature, centrifuging and washing the reactants, collecting white precipitates, activating and washing, placing the product in a vacuum oven at 80°C, and cooling to obtain a white powder of Ln-MOFs, wherein Ln is one of Tb, Eu, Dy, Sm, Pr, Ho and Er;

[0010] 2) Dispersing Ln-MOFs in PEI solution, stirring to functionalize its surface, and collecting by centrifugation to obtain Ln-MOFs@PEI.

[0011] After washing, the product was freeze-dried in vacuum to obtain Ln-MOFs@PEI powder.

[0012] In the above preparation method, in step 1), the reaction is carried out at 60° C. for 24 hours.

[0013] In the above preparation method, in step 1), the activation is to disperse the white precipitate in methanol and activate it for 24 hours.

[0014] In the above preparation method, in step 2), the concentration of the PEI solution is 1 mM, and the ratio of Ln-MOFs to PEI solution is 0.01 g:20 ml.

[0015] The above-mentioned colorimetric-luminescent dual-mode probe for copper ion detection is used in the qualitative and / or quantitative detection of copper ions.

[0016] The above application is a method for qualitatively detecting copper ions: add Ln-MOFs@PEI solution to the solution, adjust the pH to 8, and test under a spectrometer. If there are emission peaks at 546nm and 402nm, the solution contains copper ions.

[0017] Application on quantitative detection of copper ions:

[0018] 1) 500μM, 100μM, 50μM, 10μM, 5μM, 1μM, 500nM, 100nM, 50nM and 10nM CuCl2 solutions were used as test samples, 800μL Tb-MOFs@PEI was added, pH was adjusted to 8, and the samples were tested under a spectrometer to obtain the emission peak intensity ratios at 546nm and 402nm compared with Cu 2+ The linear relationship between the solution,

[0019] 2) Add 800 μL Tb-MOFs@PEI to the solution to be tested, adjust the pH to 8, and test under a spectrometer to obtain the emission peak intensity ratio at 546 nm and 402 nm. Substitute it into the linear relationship obtained in step 1) to obtain the Cu content in the solution. 2+ concentration.

[0020] The Ln-MOFs@PEI fluorescent probe can be a combination of Tb and trimesic acid, Eu and trimesic acid, Dy and trimesic acid, Sm and trimesic acid, Pr and trimesic acid, Ho and trimesic acid, Er and trimesic acid, Tb and isophthalic acid, Eu and isophthalic acid, Dy and isophthalic acid, Sm and isophthalic acid, Pr and isophthalic acid, Ho and isophthalic acid, Er and isophthalic acid, Tb and 2-aminoterephthalic acid, Eu and 2-aminoterephthalic acid, Dy and 2-aminoterephthalic acid, Sm and 2-aminoterephthalic acid, Pr and 2-aminoterephthalic acid, Ho and 2-aminoterephthalic acid, and Er and 2-aminoterephthalic acid.

[0021] The colorimetric-luminescent dual-mode probe spectrum is a multi-peak emission of a specific wavelength generated under ultraviolet or near-infrared light irradiation. For example, the Ln-MOFs@PEI probe material using Tb as the luminescence center and benzene trimetricarboxylic acid as a ligand can have two characteristic emission peaks near 545nm and 402nm, the Ln-MOFs@PEI probe material using Eu as the luminescence center and benzene trimetricarboxylic acid as a ligand can have two characteristic emission peaks near 613nm and 402nm, the Ln-MOFs@PEI probe material using Dy as the luminescence center and benzene trimetricarboxylic acid as a ligand can have two characteristic emission peaks near 574nm and 402nm, the Ln-MOFs@PEI probe material using Sm as the luminescence center and benzene trimetricarboxylic acid as a ligand can have two characteristic emission peaks near 599nm and 402nm, and the Ln-MOFs@PEI probe material using Pr as the luminescence center and benzene trimetricarboxylic acid as a ligand can have two characteristic emission peaks near 599nm and 402nm. The Ln-MOFs@PEI probe material with Ho as the luminescence center and trimesic acid as the ligand can show two characteristic emission peaks near 605nm and 402nm. The Ln-MOFs@PEI probe material with Er as the luminescence center and trimesic acid as the ligand can show two characteristic emission peaks near 456nm and 402nm. The Ln-MOFs@PEI probe material with Tb as the luminescence center and isophthalic acid as the ligand can show two characteristic emission peaks near 545nm and 402nm. The Ln-MOFs@PEI probe material with Tb as the luminescence center and isophthalic acid as the ligand can show two characteristic emission peaks near 545nm and 420nm. -aminoterephthalic acid as the ligand of Ln-MOFs@PEI probe material can show two characteristic emission peaks near 545nm and 430nm, Eu as the luminescence center and isophthalic acid as the ligand of Ln-MOFs@PEI probe material can show two characteristic emission peaks near 613nm and 420nm, Eu as the luminescence center and 2-aminoterephthalic acid as the ligand of Ln-MOFs@PEI probe material can show two characteristic emission peaks near 613nm and 430nm, Dy as the luminescence center and isophthalic acid as the ligand of Ln-MOFs@PEI probe material can show two characteristic emission peaks near 574nm and 420nm, Dy as The Ln-MOFs@PEI probe material with luminescence center and 2-aminoterephthalic acid as ligand can show two characteristic emission peaks near 574nm and 430nm. The Ln-MOFs@PEI probe material with Sm as luminescence center and isophthalic acid as ligand can show two characteristic emission peaks near 599nm and 420nm. The Ln-MOFs@PEI probe material with Sm as luminescence center and 2-aminoterephthalic acid as ligand can show two characteristic emission peaks near 599nm and 430nm. The Ln-MOFs@PEI probe material with Pr as luminescence center and isophthalic acid as ligand can show two characteristic emission peaks near 605nm and 420nm.The Ln-MOFs@PEI probe material with Pr as the luminescence center and 2-aminoterephthalic acid as the ligand can show two characteristic emission peaks near 605nm and 430nm, the Ln-MOFs@PEI probe material with Ho as the luminescence center and isophthalic acid as the ligand can show two characteristic emission peaks near 456nm and 420nm, the Ln-MOFs@PEI probe material with Ho as the luminescence center and 2-aminoterephthalic acid as the ligand can show two characteristic emission peaks near 456nm and 430nm, the Ln-MOFs@PEI probe material with Er as the luminescence center and isophthalic acid as the ligand can show two characteristic emission peaks near 545nm and 420nm, the Ln-MOFs@PEI probe material with Er as the luminescence center and 2-aminoterephthalic acid as the ligand can show two characteristic emission peaks near 545nm and 430nm. ,

[0022] Ln-MOFs@PEI colorimetric-luminescent dual-mode probe has the following advantages:

[0023] Ln-MOFs@PEI will change color in copper solution but will not change significantly in other ions. Therefore, Ln-MOFs@PEI can be used as a colorimetric probe for copper ions. Moreover, the luminescence intensity of Ln-MOFs@PEI in copper solution is inversely proportional to the concentration of copper ions. Therefore, Ln-MOFs@PEI can be used as a colorimetric-luminescence dual-mode probe for detecting copper ions, which increases the accuracy and reliability of detecting copper ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the XRD pattern of Ln-MOFs.

[0025] Figure 2 To add different concentrations of Cu 2+ Emission spectrum of Ln-MOFs@PEI solution.

[0026] Figure 3 For I 546 nm / I 402 nm With Cu 2+ The linear relationship between them.

[0027] Figure 4 The selective luminescence intensity change of Ln-MOFs@PEI probe to copper ions.

[0028] Figure 5 This is the color change of the copper ion solvent after the Ln-MOFs@PEI probe is placed in it. DETAILED DESCRIPTION

[0029] Example 1 Preparation of Tb-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0030] 1) Preparation of Tb-MOFs by hot solvent method: 0.0093g Tb(NO3)3, 0.3524g Y(NO3)3 and 0.0014g CH3COONa were dissolved in 22.6mL deionized water. The solution was ultrasonicated with 0.1051g benzenetricarboxylic acid and 40mL DMF solution for 30 minutes to obtain a white solution. The white solution was added to the reactor, placed at 60°C for 24 hours, and then cooled to room temperature. The reactants were centrifuged and washed with DMF 3 times. The white precipitate was collected and then dispersed in 50mL methanol for activation for 24 hours. Finally, it was washed 3 times with methanol. The product was placed in a vacuum oven at 80°C for 12 hours to obtain a white powder of Tb-MOFs. Figure 1 is the XRD spectrum of Tb-MOFs. The diffraction peaks correspond to those of the JUC-32 standard card, which means that Tb 3+ and Y 3+ The concentration change has no effect on the crystal structure.

[0031] 2) Disperse 0.1 g of Tb-MOFs in PEI solution (1 mM, 20 mL) and stir at room temperature for 2 hours to functionalize its surface. Collect Tb-MOFs@PEI by centrifugation and wash with deionized water three times. Place the product in a vacuum freeze dryer for 24 hours to obtain a powder sample of Tb-MOFs@PEI.

[0032] 3) A series of specific concentrations (500 μM, 100 μM, 50 μM, 10 μM, 5 μM, 1 μM, 500 nM, 100 nM, 50 nM and 10 nM) of CuCl2 solution were used as the test samples. 200 μL of specific concentration of Cu 2+ The solution was added to a cuvette, and then 800 μL of Tb-MOFs@PEI was placed in the dispersion and the pH was adjusted to 8. After ultrasonic homogenization, the sample was tested under a spectrometer. Figure 2 For Ln-MOFs@PEI in Cu 2+ The luminescence spectrum in the solution shows that the emission peak intensity ratio at 546nm and 402nm shows an opposite trend with the increase of copper ion concentration. This is due to the difference in luminescence quenching mechanism.

[0033] Tb-MOFs@PEI has two characteristic emission peaks near 545nm and 402nm under the excitation of ultraviolet light. When Tb-MOFs@PEI is added to copper ion solutions of different concentrations, the emission peak intensities at 545nm and 402nm will change. The concentration of copper ions is detected by the fluorescence intensity ratio of 545nm and 402nm. Figure 3The emission peak intensity ratio at 546nm and 402nm is compared with that of Cu 2+ The linear relationship between the solution and Cu 2+ The detection range is 5nM-100μM, and the detection limit is 9.7nM. Prepare CuCl2, AlCl3, BaCl2, PbCl2, CaCl2, ZnCl2, HCl, HNO3, CH3COOH, H3PO4 and H2SO4 solutions. When Tb-MOFs@PEI is added to the above solutions, only the luminescence intensity of CuCl2 solution changes, while the luminescence intensity of other solutions does not change ( Figure 4 ). Figure 5 For Tb-MOFs@PEI dispersed in different concentrations of Cu 2+ The color of the solution changes when the solution is dissolved.

[0034] The following examples are for Cu 2+ The detection method is the same as follows:

[0035] Example 2 Preparation of Eu-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0036] The 0.0093 g Tb(NO3)3 in step 1) of Example 1 was replaced with 0.0091 g Eu(NO3)3, and the other steps and operations remained unchanged.

[0037] Eu-MOFs@PEI has two characteristic emission peaks near 613nm and 402nm under the excitation of ultraviolet light. When Eu-MOFs@PEI is added to copper ion solutions of different concentrations, the emission peak intensities at 613nm and 402nm will change. The concentration of copper ions is detected by the fluorescence intensity ratio of 613nm and 402nm.

[0038] Example 3 Preparation of Dy-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0039] The 0.0093 g Tb(NO3)3 in step 1) of Example 1 was replaced with 0.0093 g Dy(NO3)3, and the other steps and operations remained unchanged.

[0040] Dy-MOFs@PEI has two characteristic emission peaks near 574nm and 402nm under the excitation of ultraviolet light. When Dy-MOFs@PEI is added to copper ion solutions of different concentrations, the emission peak intensities at 574nm and 402nm will change. The concentration of copper ions is detected by the fluorescence intensity ratio of 574nm and 402nm.

[0041] Example 4 Preparation of Sm-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0042] The 0.0093 g Tb(NO3)3 in step 1) of Example 1 was replaced with 0.0111 g Sm(NO3)3, and the other steps and operations remained unchanged.

[0043] Sm-MOFs@PEI has two characteristic emission peaks near 599nm and 402nm under the excitation of ultraviolet light. When Sm-MOFs@PEI is added to copper ion solutions of different concentrations, the emission peak intensities at 599nm and 402nm will change. The concentration of copper ions is detected by the fluorescence intensity ratio of 599nm and 402nm.

[0044] Example 5 Preparation of Pr-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0045] The 0.0093 g Tb(NO3)3 in step 1) of Example 1 was replaced with 0.0109 g Pr(NO3)3, and the other steps and operations remained unchanged.

[0046] Pr-MOFs@PEI has two characteristic emission peaks near 605nm and 402nm under the excitation of ultraviolet light. When Pr-MOFs@PEI is added to copper ion solutions of different concentrations, the emission peak intensities at 605nm and 402nm will change. The concentration of copper ions is detected by the fluorescence intensity ratio of 605nm and 402nm.

[0047] Example 6 Preparation of Ho-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0048] The 0.0093 g Tb(NO3)3 in step 1) of Example 1 was replaced with 0.0079 g Ho(NO3)3, and the other steps and operations remained unchanged.

[0049] Ho-MOFs@PEI has two characteristic emission peaks near 456nm and 402nm under the excitation of 980nm. When Ho-MOFs@PEI is added to copper ion solutions of different concentrations, the emission peak intensities at 456nm and 402nm will change. The concentration of copper ions is detected by the fluorescence intensity ratio of 456nm and 402nm.

[0050] Example 7 Preparation of Er-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0051] The 0.0093 g Tb(NO3)3 in step 1) of Example 1 was replaced with 0.0115 g Er(NO3)3, and the other steps and operations remained unchanged.

[0052] Er-MOFs@PEI has two characteristic emission peaks near 545nm and 402nm under the excitation of 980nm. When Er-MOFs@PEI is added to copper ion solutions of different concentrations, the emission peak intensities at 545nm and 402nm will change. The concentration of copper ions is detected by the fluorescence intensity ratio of 545nm and 402nm.

[0053] Example 8 Preparation of Tb-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0054] In step 1) of Example 1, 0.1051 g of trimesic acid was replaced with 0.0083 g of isophthalic acid, and the remaining steps and operations remained unchanged.

[0055] Example 9 Preparation of Tb-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0056] In step 1) of Example 1, 0.1051 g of trimesic acid was replaced with 0.0091 g of 2-aminoterephthalic acid, and the remaining steps and operations remained unchanged.

[0057] Example 10 Preparation of Eu-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0058] The 0.1051 g of trimesic acid in the step of Example 2 was replaced with 0.0083 g of isophthalic acid, and the other steps and operations remained unchanged.

[0059] Example 11 Preparation of Eu-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0060] In the step of Example 2, 0.1051 g of trimesic acid was replaced with 0.0091 g of 2-aminoterephthalic acid, and the remaining steps and operations remained unchanged.

[0061] Example 12 Preparation of Dy-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0062] In the step of Example 3, 0.1051 g of trimesic acid was replaced with 0.0083 g of isophthalic acid, and the other steps and operations remained unchanged.

[0063] Example 13 Preparation of Dy-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0064] In the step of Example 3, 0.1051 g of trimesic acid was replaced with 0.0091 g of 2-aminoterephthalic acid, and the other steps and operations remained unchanged.

[0065] Example 14 Preparation of Sm-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0066] In the step of Example 4, 0.1051 g of trimesic acid was replaced with 0.0083 g of isophthalic acid, and the other steps and operations remained unchanged.

[0067] Example 15 Preparation of Sm-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0068] In the step of Example 4, 0.1051 g of trimesic acid was replaced with 0.0091 g of 2-aminoterephthalic acid, and the other steps and operations remained unchanged.

[0069] Example 16 Preparation of Pr-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0070] In the step of Example 5, 0.1051 g of trimesic acid was replaced with 0.0083 g of isophthalic acid, and the other steps and operations remained unchanged.

[0071] Example 17 Preparation of Pr-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0072] In the step of Example 5, 0.1051 g of trimesic acid was replaced with 0.0091 g of 2-aminoterephthalic acid, and the other steps and operations remained unchanged.

[0073] Example 18 Preparation of Ho-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0074] The 0.1051 g of trimesic acid in the step of Example 6 was replaced with 0.0083 g of isophthalic acid, and the other steps and operations remained unchanged.

[0075] Example 19 Preparation of Ho-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0076] In the step of Example 6, 0.1051 g of trimesic acid was replaced with 0.0091 g of 2-aminoterephthalic acid, and the other steps and operations remained unchanged.

[0077] Example 20 Preparation of Er-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0078] In the step of Example 7, 0.1051 g of trimesic acid was replaced with 0.0083 g of isophthalic acid, and the other steps and operations remained unchanged.

[0079] Example 21 Preparation of Er-MOFs@PEI colorimetric-fluorescent dual-mode probe

[0080] In the step of Example 7, 0.1051 g of trimesic acid was replaced with 0.0091 g of 2-aminoterephthalic acid, and the other steps and operations remained unchanged.

Claims

1. A colorimetric-luminescent dual-mode probe for copper ion detection, characterized in that: It is a composite material with rare earth elements as the luminescent center and ligand-coated polyethyleneimine PEI.

2. A colorimetric-luminescent dual-mode probe for copper ion detection according to claim 1, characterized in that: The rare earth element is one of Tb, Eu, Dy, Sm, Pr, Ho, and Er ions.

3. A colorimetric-luminescent dual-mode probe for copper ion detection according to claim 1, characterized in that: The ligand is one of trimesic acid, isophthalic acid and 2-aminoterephthalic acid.

4. The method for preparing a colorimetric-luminescent dual-mode probe for copper ion detection according to any one of claims 1 to 3, characterized in that: The steps include: 1) dissolving Ln(NO3)3, Y(NO3)3 and sodium acetate in deionized water, adding ligand and DMF solution and ultrasonicating to obtain a white solution, adding the white solution into a reactor for reaction, then cooling to room temperature, centrifuging and washing the reactants, collecting white precipitates, activating and washing, placing the product in a vacuum oven at 80°C, and cooling to obtain a white powder of Ln-MOFs, wherein Ln is one of Tb, Eu, Dy, Sm, Pr, Ho and Er; 2) Dispersing Ln-MOFs in PEI solution, stirring to functionalize its surface, collecting by centrifugation to obtain Ln-MOFs@PEI, washing, and vacuum freeze-drying the product to obtain Ln-MOFs@PEI powder.

5. The preparation method according to claim 4, characterized in that: In step 1), the reaction is carried out at 60° C. for 24 hours.

6. The preparation method according to claim 4, characterized in that: In step 1), the activation is to disperse the white precipitate in methanol and activate it for 24 hours.

7. The preparation method according to claim 4, characterized in that: In step 2), the concentration of the PEI solution is 1 mM, The ratio of Ln-MOFs to PEI solution was 0.01 g:20 ml.

8. Use of the colorimetric-luminescent dual-mode probe for copper ion detection according to any one of claims 1 to 3 in the qualitative and / or quantitative detection of copper ions.

9. The use according to claim 8, characterized in that: Qualitative detection method of copper ions: add The Ln-MOFs@PEI solution was adjusted to pH = 8 and tested under a spectrometer. There were emission peaks at 546nm and 402nm, indicating that the solution contained copper ions.

10. The use according to claim 8, characterized in that: Method for quantitative detection of copper ions: 1) 500μM, 100μM, 50μM, 10μM, 5μM, 1μM, 500nM, 100nM, 50nM and 10nM CuCl2 solutions were used as test samples, 800μL Tb-MOFs@PEI was added, pH was adjusted to 8, and the samples were tested under a spectrometer to obtain the emission peak intensity ratios at 546nm and 402nm compared with Cu 2+ The linear relationship between the solution, 2) Add 800 μL Tb-MOFs@PEI to the solution to be tested, adjust the pH to 8, and test under a spectrometer to obtain the emission peak intensity ratio at 546 nm and 402 nm. Substitute it into the linear relationship obtained in step 1) to obtain the Cu content in the solution. 2+ concentration.

Images