Heavy metal ion detection method based on aggregation-induced enhanced fluorescence sensing array

Abstract

The invention provides a heavy metal ion detection method based on an aggregation-induced enhanced fluorescence sensing array. Three ligand-protected AuNCs (GSH-AuNCs, MPA-AuNCs and [2-MBA]-AuNCs) are firstly prepared and are embedded into ZIF-8 through a coordination reaction, different fluorescence intensity adjustment degrees of the three sensing elements by heavy metal ions are used as output signals, and the heavy metal ions are used for detecting the fluorescence intensity of the three sensing elements. According to the method, linear discriminant analysis (LDA) and hierarchical clustering analysis (HCA) are used for analysis to obtain unique spectrum fingerprint data of each heavy metal ion, a database for identifying eight heavy metal ions is successfully established, software SPSS Statistics 27 is used for processing the obtained data, the unique spectrum fingerprint data of each heavy metal ion is obtained, and the spectrum fingerprint data of each heavy metal ion is obtained. Therefore, accurate identification and sensitive quantitative detection of eight heavy metal ions (Ni < 2 + >, Cr < 2 + >, Co < 2 + >, Pb < 2 + >, Cd < 2 + >, Ag < + >, Cu < 2 + > and Zn < 2 + >) are realized.

Description

Technical Field

[0001] The invention relates to the field of heavy metal ion detection in water environment, and in particular to a heavy metal ion detection method based on an aggregation-induced enhanced fluorescence sensor array. Background Art

[0002] Heavy metal ions generated in industrial activities are usually difficult to biodegrade, and then cause harm to human health through the food chain. Therefore, accurate quantification of multiple heavy metal ions in complex environments is crucial to environmental protection and human health. Several established instrumental methods, such as X-ray fluorescence spectroscopy (XRF), atomic absorption spectroscopy (AAS), and inductively coupled plasma mass spectrometry (ICP-MS), can be used to detect heavy metal ions, but the operating procedures are cumbersome, rely on large instruments, and it is difficult to achieve simultaneous identification of multiple heavy metal ions. The same is true for traditional specific sensing methods. Therefore, it is necessary to develop a new method that can simultaneously identify and accurately quantify multiple heavy metal ions.

[0003] Sensor arrays, also known as "chemical noses", are composed of multiple semi-selective sensing elements that can generate a unique "fingerprint" for each analyte. Linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA) are used to intelligently classify data to obtain "fingerprint" information to achieve the purpose of distinguishing multiple analytes. Among them, the recognition element is the cornerstone of the analytical performance of the sensor array and is crucial to the analytical performance of the sensor array. Among these sensing elements, gold nanoclusters (AuNCs) stand out due to their unique optical properties and programmability of surface ligands. However, since the luminescence efficiency of AuNCs is affected by the vibration and spin of the intramolecular ligands, the fluorescence quantum yield of the sensor array based on nanoclusters is low and the analytical performance is weak. At present, there are many attempts to improve the luminescence efficiency of AuNCs. For example, in-situ selective doping of silver atoms in AuNCs is performed to improve the luminescence efficiency by reducing non-radiative losses. However, noble metal doping increases the experimental cost and the luminescence efficiency is also limited. Summary of the invention

[0004] In order to solve the problems in the prior art, the present invention provides a heavy metal ion detection method based on aggregation-induced enhanced fluorescence sensor array. The present invention first prepares three ligand-protected AuNCs (GSH-AuNCs, MPA-AuNCs and [2-MBA]-AuNCs), and embeds them into ZIF-8 through coordination reaction, uses the different degree of fluorescence intensity regulation of the three sensor elements by heavy metal ions as output signals, uses linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA) to obtain unique spectral fingerprint data for each heavy metal ion, successfully establishes a database for identifying eight heavy metal ions, and then uses software SPSS Statistics 27 to process the obtained data to obtain unique spectral fingerprint data for each heavy metal ion, so as to achieve eight heavy metal ions (Ni 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2+ 、Ag + , Cu 2+ and Zn 2+ ) for accurate identification and sensitive quantitative detection.

[0005] The technical solutions adopted to achieve the above objectives are as follows:

[0006] A heavy metal ion detection method based on an aggregation-induced enhanced fluorescence sensor array includes the preparation of three sensor elements, the construction of an aggregation-induced enhanced fluorescence sensor array and data processing steps; the three sensor elements are glutathione-gold nanoclusters@zeolite imidazolate framework material (GSH-AuNCs@ZIF-8), mercaptopropionic acid-gold nanoclusters@zeolite imidazolate framework material (MPA-AuNCs@ZIF-8) and (2-mercaptobenzoic acid)-gold nanoclusters@zeolite imidazolate framework material ([2-MBA]-AuNCs@ZIF-8).

[0007] The preparation steps of the glutathione-gold nanocluster@zeolite imidazolate framework material (GSH-AuNCs@ZIF-8) are as follows:

[0008] HAuCl 4 ·3H 2 O solution and GSH solution were added to deionized water and mixed, and stirred at 300-600 rpm for 22-26 hours at 60-80°C to obtain glutathione-gold nanocluster (GSH-AuNCs) solution; zinc nitrate (Zn[NO 3 ] 2) aqueous solution, ultrasonically disperse for 20 to 40 minutes, then add 2-methylimidazole (2-MeIm) aqueous solution, stir the mixture vigorously for 22 to 26 hours, centrifuge and separate, wash the precipitate with methanol and dry it in a vacuum at 50 to 70°C.

[0009] Specifically, the preparation steps of glutathione-gold nanoclusters@zeolite imidazolate framework material (GSH-AuNCs@ZIF-8) are as follows: HAuCl 4 ·3H 2 O solution and GSH solution were added to deionized water and mixed evenly, and stirred at 70 °C and 500 rpm for 24 h to obtain glutathione-gold nanocluster (GSH-AuNCs) solution. Zinc nitrate (Zn[NO 3 ] 2 ) aqueous solution and ultrasonically dispersed for 30 minutes, then added with 2-methylimidazole (2-MeIm) aqueous solution, the mixture was vigorously stirred for 24 hours, centrifuged and the precipitate was washed three times with methanol and dried in a vacuum at 60°C for 8 hours.

[0010] The preparation steps of the mercaptopropionic acid-gold nanocluster@zeolite imidazolate framework material (MPA-AuNCs@ZIF-8) are as follows:

[0011] Dilute HAuCl with deionized water 4 ·3H 2 O solution, add MPA and NaOH solution, and stir the mixture at room temperature for 0.5-1.5h to obtain a mercaptopropionic acid-gold nanocluster (MPA-AuNCs) solution; add zinc nitrate (Zn[NO 3 ] 2 ) aqueous solution, ultrasonically disperse for 20 to 40 minutes, then add 2-methylimidazole (2-MeIm) aqueous solution, stir the mixture vigorously for 22 to 26 hours, centrifuge and separate, wash the precipitate with methanol and dry it in a vacuum at 50 to 70°C.

[0012] Specifically, the preparation steps of mercaptopropionic acid-gold nanoclusters@zeolite imidazolate framework material (MPA-AuNCs@ZIF-8) are as follows: dilute HAuCl 4 ·3H 2 O solution, followed by the addition of MPA and NaOH solutions, and the mixture was stirred at room temperature for 1 h to obtain a mercaptopropionic acid-gold nanocluster (MPA-AuNCs) solution; the mercaptopropionic acid-gold nanocluster (MPA-AuNCs) solution was added with zinc nitrate (Zn[NO 3 ] 2) aqueous solution, ultrasonically disperse for 30 minutes, then add 2-methylimidazole (2-MeIm) aqueous solution, stir the mixture vigorously for 24 hours, centrifuge and separate the precipitate. Wash the precipitate with methanol for 3 times and dry it in vacuum at 60°C for 8 hours.

[0013] The preparation steps of the (2-mercaptobenzoic acid)-gold nanocluster@zeolite imidazolate framework material ([2-MBA]-AuNCs@ZIF-8) are as follows: 2-MBA is dissolved in deionized water, and NaOH solution is added, and then HAuCl is added. 4 ·3H 2 O solution was mixed evenly and stirred at 20-30°C for 6-10 hours to obtain a (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution; the (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution was added with zinc nitrate (Zn[NO 3 ] 2 ) aqueous solution, ultrasonically disperse for 20 to 40 minutes, then add 2-methylimidazole (2-MeIm) aqueous solution, stir the mixture vigorously for 22 to 26 hours, centrifuge and separate, wash the precipitate with methanol and dry it in a vacuum at 50 to 70°C.

[0014] Specifically, the preparation steps of (2-mercaptobenzoic acid)-gold nanoclusters@zeolite imidazolate framework material ([2-MBA]-AuNCs@ZIF-8) are as follows: 2-MBA is dissolved in deionized water, and NaOH solution is added, and then HAuCl is added. 4 ·3H 2 O solution was mixed evenly and stirred at 25 °C for 8 h to obtain a (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution; the (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution was added with zinc nitrate (Zn[NO 3 ] 2 ) aqueous solution, ultrasonically disperse for 30 minutes, then add 2-methylimidazole (2-MeIm) aqueous solution, stir the mixture vigorously for 24 hours, centrifuge and separate the precipitate. Wash the precipitate with methanol for 3 times and dry it in vacuum at 60°C for 8 hours.

[0015] According to one embodiment of the present invention, the zinc nitrate (Zn[NO 3 ] 2 ), 2-methylimidazole (2-MeIm) and deionized water in a ratio of 1:50-70:1100-1200, in terms of mass percentage. 3 ] 2 ), 2-methylimidazole (2-MeIm) and deionized water were maintained at a ratio of 1:60:1150.

[0016] According to one embodiment of the present invention, the aggregation-induced enhanced fluorescence sensor array is constructed by adding solutions of three sensor elements and heavy metal ion solution into a centrifuge tube, incubating the mixed solution at 20-30°C for 30-50 minutes, and then detecting the fluorescence intensity of the system by an ELISA instrument to obtain a training data matrix.

[0017] According to one embodiment of the present invention, the aggregation-induced enhanced fluorescence sensor array is constructed as follows: solutions of three sensor element materials, heavy metal ion solution, and buffer solution are sequentially added to a centrifuge tube, the mixed solution is incubated at 25°C for 40 minutes, and then the fluorescence intensity of the system is detected by an ELISA instrument to obtain a training data matrix of 3 sensor elements × 8 heavy metal ions × 5 repetitions.

[0018] According to one embodiment of the present invention, the solution of the three sensor element materials (gold nanoclusters @ zeolite imidazolate framework material) is added at a concentration of 0.1 mg / mL and a volume of 50 μL; the heavy metal ion solution is added in a volume of 50 μL; and the Tris-HCl buffer or HEPES buffer is added in a volume of 900 μL.

[0019] According to one embodiment of the present invention, the data processing is to use the software SPSS Statistics 27 to process the obtained data to obtain unique spectral fingerprint data for each heavy metal ion, accurately distinguish and quantify eight heavy metal ions; the eight heavy metal ions are Ni 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2+ 、Ag + , Cu 2+ and Zn 2+ .

[0020] Beneficial effects:

[0021] The present invention first developed three types of gold nanoclusters @ zeolite imidazolate framework materials as sensing elements and constructed an aggregation-induced enhanced fluorescence sensing array. Since the eight heavy metal ions have different binding effects with the three sensing elements, the fluorescence intensity of the gold nanoclusters @ zeolite imidazolate framework materials is adjusted to different degrees, and the heavy metal ions can be distinguished after further analysis by statistical analysis methods. The sensor array can accurately identify eight heavy metal ions in the concentration range of 0.5 to 50 μM, and can also identify multi-component mixtures of heavy metal ions. It has excellent distinguishing ability not only in tap water, but also in complex Chinese medicine samples such as astragalus and angelica, and has very important application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : The fluorescence spectra of the present invention, including (A) fluorescence excitation and emission spectra of GSH-AuNCs@ZIF-8, (B) fluorescence excitation and emission spectra of MP A-AuNCs@ZIF-8 and (C) fluorescence excitation and emission spectra of (2-MBA)-AuNCs@ZIF-8.

[0023] Figure 2 The fingerprint spectrum is formed by the recognition results of eight heavy metal ions by the sensor array in the present invention.

[0024] Figure 3 The detection results of the sensor array in the present invention for eight heavy metal ions of different concentrations, including (A) 50 μM LDA typical score graph of the eight heavy metal ions, (B) 10 μM LDA typical score graph of the eight heavy metal ions, (C) 1 μM LDA typical score graph of the eight heavy metal ions and (D) 0.5 μM LDA typical score graph of the eight heavy metal ions.

[0025] Figure 4 The three-dimensional typical scoring diagram of the sensor array of the present invention for several single heavy metal ions and a mixture of multiple heavy metal ions.

[0026] Figure 5 The sensor array of the present invention detects heavy metal ions in (A) tap water sample, (A) astragalus sample and (C) angelica sample. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0028] 1. Preparation of glutathione-gold nanoclusters@zeolite imidazolate framework materials (GSH-AuNCs@ZIF-8), mercaptopropionic acid-gold nanoclusters@zeolite imidazolate framework materials (MPA-AuNCs@ZIF-8) and (2-mercaptobenzoic acid)-gold nanoclusters@zeolite imidazolate framework materials ([2-MBA]-AuNCs@ZIF-8)

[0029] Preparation of glutathione-gold nanoclusters@zeolite imidazolate framework (GSH-AuNCs@ZIF-8): HAuCl 4 ·3H 2O solution (0.5 mL, 20 mM) and GSH solution (0.15 mL, 100 mM) were mixed into 4.35 mL of deionized water. The resulting mixture was stirred at 70 °C and 500 rpm for 24 h to obtain a glutathione-gold nanocluster (GSH-AuNCs) solution. The glutathione-gold nanocluster (GSH-AuNCs) solution was added with zinc nitrate (Zn[NO 3 ] 2 ) aqueous solution, ultrasonically dispersed for 30 min, and then added 2-methylimidazole (2-MeIm) aqueous solution. Zinc nitrate (Zn[NO 3 ] 2 ), 2-methylimidazole (2-MeIm) and deionized water in a ratio of about 1:60:1150. Finally, the mixture was vigorously stirred for 24 h, centrifuged, washed with methanol three times, and dried in a vacuum at 60 °C for 8 h.

[0030] Preparation of mercaptopropionic acid-gold nanoclusters@zeolite imidazolate framework (MPA-AuNCs@ZIF-8): HAuCl was diluted with 68.64 mL of deionized water. 4 ·3H 2 O solution (0.8 mL, 20 mM), followed by MPA (9.6 mL, 10 mM) and NaOH solution (0.96 mL, 100 mM), and the mixture was stirred at room temperature for 1 h to obtain a mercaptopropionic acid-gold nanocluster (MPA-AuNCs) solution. The mercaptopropionic acid-gold nanocluster (MPA-AuNCs) solution was added with zinc nitrate (Zn[NO 3 ] 2 ) aqueous solution, ultrasonically dispersed for 30 min, and then added 2-methylimidazole (2-MeIm) aqueous solution. Zinc nitrate (Zn[NO 3 ] 2 ), 2-methylimidazole (2-MeIm) and deionized water in a ratio of about 1:60:1150. Finally, the mixture was vigorously stirred for 24 h, centrifuged, washed with methanol three times, and dried in a vacuum at 60 °C for 8 h.

[0031] (2-Mercaptobenzoic acid)-gold nanoclusters@zeolite imidazolate framework material ([2-MBA]-AuNCs@ZIF-8): 2-MBA (30.8 mg) was completely dissolved in 3.84 mL of deionized water, and NaOH solution (0.16 mL, 5 M) was added to finally obtain a 2-MBA solution with a concentration of 50 mM. HAuCl 4 ·3H 2O solution (4 mL, 20 mM) was mixed into the above solution and stirred at 25 °C for 8 h to obtain a (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution. The (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution was added with zinc nitrate (Zn[NO 3 ] 2 ) aqueous solution, ultrasonically dispersed for 30 min, and then added 2-methylimidazole (2-MeIm) aqueous solution. Zinc nitrate (Zn[NO 3 ] 2 ), 2-methylimidazole (2-MeIm) and deionized water in a ratio of about 1:60:1150. Finally, the mixture was vigorously stirred for 24 h, centrifuged, washed with methanol three times, and dried in a vacuum at 60 °C for 8 h.

[0032] 2. Determination of optical properties of GSH-AuNCs@ZIF-8, MPA-AuNCs@ZIF-8 and (2-MBA)-AuNCs@ZIF-8

[0033] By fluorescence spectrometer, Figure 1 As shown in A, it can be seen that GSH-AuNCs@ZIF-8 has a maximum fluorescence intensity at an excitation wavelength of 390 nm and an emission wavelength of 620 nm. Figure 1 As shown in B, it can be seen that the fluorescence intensity of MPA-AuNCs@ZIF-8 reaches the maximum at the excitation wavelength of 290nm and the emission wavelength of 581nm. Figure 1 As shown in Figure C, it can be seen that (2-MBA)-AuNCs@ZIF-8 has maximum fluorescence intensity at the excitation wavelength of 323 nm and the emission wavelength of 640 nm.

[0034] 3. Construction of Aggregation-Induced Enhanced Fluorescence Sensor Array and Detection of Heavy Metal Ions

[0035] The three sensing elements produce fluorescent responses to heavy metal ions: freshly prepared Ni 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2 + 、Ag + , Cu 2+ and Zn 2+Aqueous solution (final concentration of 10 μM). Add 50 μL of gold nanocluster @ zeolite imidazolate framework material solution, 50 μL of heavy metal ion solution and 900 μL of Tris-HCl buffer or HEPES buffer to the centrifuge tubes respectively, mix and incubate at 25°C for 40 minutes, and measure the fluorescence intensity of the three sensor elements after adding heavy metal ions at the selected wavelength. Different heavy metal ions show different effects on the fluorescence intensity of different sensor elements.

[0036] Detection of eight heavy metal ions using an aggregation-induced enhanced fluorescence sensor array: Preparation of Ni 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2+ 、Ag + , Cu 2+ and Zn 2+ Aqueous solution (final concentrations of 50 μM, 10 μM, 1 μM, and 0.5 μM, respectively). Add 50 μL of gold nanocluster @ zeolite imidazole ester framework material solution, 50 μL of heavy metal ion solution, and 900 μL of Tris-HCl buffer or HEPES buffer to the centrifuge tubes, mix and incubate at 25°C for 40 minutes, and repeat the test five times. Set the excitation and emission wavelengths in the microplate reader to measure the fluorescence intensity of the three sensor elements after adding heavy metal ions. Finally, a training data matrix of 3 sensor elements × 8 heavy metal ions × 5 repetitions was obtained.

[0037] Detection of heavy metal ion mixtures using the sensor array with aggregation-induced enhanced fluorescence: In order to further verify the multiple detection capabilities of the sensor array, this experiment will use the sensor array to detect heavy metal ion multi-component mixtures. Freshly prepared aqueous solutions of five single metal ions and their multi-component mixtures (Cu 2+ / Cr 2+ / Ag + / Ni 2+ / Pb 2+ ). Add 50 μL of gold nanocluster@zeolite imidazolate framework material solution, 50 μL of heavy metal ion solution and 900 μL of Tris-HCl buffer or HEPES buffer to the centrifuge tubes respectively, mix and incubate at 25°C for 40 min, and repeat the test five times. Set the excitation and emission wavelengths in the microplate reader and measure the fluorescence intensity of the three sensor elements after adding heavy metal ions.

[0038] Detection of heavy metal ions in actual samples using the sensor array of aggregation-induced enhanced fluorescence: In order to further verify the detection capability of the sensor array in complex environments, this experiment will use the sensor array to detect heavy metal ions in tap water and traditional Chinese medicine. The tap water collected was filtered through a 0.22μM microporous filter membrane as a solvent to prepare eight heavy metal ion aqueous solutions with a final concentration of 10μM (Ni 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2+ 、Ag + , Cu 2+ and Zn 2+ ). Add 50 μL of gold nanocluster@zeolite imidazolate framework material solution, 50 μL of heavy metal ion solution and 900 μL of Tris-HCl buffer or HEPES buffer to the centrifuge tubes respectively, mix and incubate at 25°C for 40 min, and repeat the test five times. Set the excitation and emission wavelengths in the microplate reader to measure the fluorescence intensity of the three sensor elements after adding heavy metal ions. Finally, a training data matrix of 3 sensor elements × 8 heavy metal ions × 5 repetitions was obtained.

[0039] 4. Process the obtained data based on the software SPSS Statistics 27

[0040] The sensor array using aggregation-induced enhanced fluorescence was used to detect eight heavy metal ions: the training data matrix of four final concentrations (3 sensor elements × 8 heavy metal ions × 5 repetitions) was processed by the software. For 50 μM heavy metal ions, Figure 2 As shown in A, in the LDA two-dimensional score diagram, factor 1 and factor 2 are 80.2% and 19.3% respectively; for 10 μM heavy metal ions, Figure 2 As shown in B, in the LDA two-dimensional score diagram, factor 1 and factor 2 are 74.8% and 24.7% respectively; for 1 μM heavy metal ions, Figure 2 As shown in C, in the LDA two-dimensional score diagram, factor 1 and factor 2 are 94.8% and 4.7% respectively; for 0.5 μM heavy metal ions, Figure 2 As shown in D, in the LDA two-dimensional scoring diagram, factor 1 and factor 2 are 93.0% and 6.5% respectively. It can be seen that the sensor array of the present invention can correctly distinguish heavy metal ions. Figure 3 As shown, each heavy metal ion has its own unique "fingerprint", indicating that the constructed aggregation-induced enhanced fluorescence sensing array is highly feasible in distinguishing heavy metal ions.

[0041] Detection of heavy metal ion mixtures using aggregation-induced enhanced fluorescence sensing arrays: Targeting Cu 2+ / Cr 2+ / Ag+ / Ni 2+ / Pb 2+ The training data matrix is ​​processed by the software, such as Figure 4 As shown, the first two typical discrimination factors in the three-dimensional scoring graph are 98.2% and 1.2%, demonstrating the multiple recognition capability of the sensor array.

[0042] The sensor array using aggregation-induced enhanced fluorescence was used to detect heavy metal ions in real samples: in tap water, astragalus and angelica samples, the training data matrix (3 sensor elements × 8 heavy metal ions × 5 repetitions) was processed by the software, as shown in Figure 5 As shown in the figure, the eight heavy metal ions are well distinguished in the LDA score graph. Figure 5 As shown in A, factor 1 and factor 2 are 90.3% and 7.7% respectively; for the heavy metal ions in the precipitate of the Astragalus sample, Figure 5 As shown in B, factor 1 and factor 2 are 97.6% and 1.4% respectively; for the heavy metal ions in the precipitate of Angelica sinensis sample, Figure 5 As shown in Figure C, factor 1 and factor 2 are 77.7% and 13.8%, respectively, which further demonstrates that the constructed aggregation-induced enhanced fluorescence sensor array can distinguish heavy metal ions in complex environments.

Claims

1. A heavy metal ion detection method based on an aggregation-induced enhanced fluorescence sensor array, comprising the steps of preparing three sensor elements, constructing an aggregation-induced enhanced fluorescence sensor array and processing data; the three sensor elements are glutathione-gold nanoclusters@zeolite imidazolate framework material (GSH-AuNCs@ZIF-8), mercaptopropionic acid-gold nanoclusters@zeolite imidazolate framework material (MPA-AuNCs@ZIF-8) and (2-mercaptobenzoic acid)-gold nanoclusters@zeolite imidazolate framework material ([2-MBA]-AuNCs@ZIF-8); The preparation steps of the glutathione-gold nanocluster @ zeolite imidazole ester framework material (GSH-AuNCs@ZIF-8) are as follows: HAuCl4·3H2O solution and GSH solution are added to deionized water for mixing, and stirred at 300-600 rpm for 22-26 hours at 60-80°C to obtain a glutathione-gold nanocluster (GSH-AuNCs) solution; the glutathione-gold nanocluster (GSH-AuNCs) solution is added to a zinc nitrate (Zn[NO3]2) aqueous solution, ultrasonically dispersed for 20-40 minutes, and then a 2-methylimidazole (2-MeIm) aqueous solution is added, the mixture is vigorously stirred for 22-26 hours, centrifuged, the precipitate is washed with methanol, and dried in a vacuum at 50-70°C to obtain the obtained product; The preparation steps of the MPA-AuNCs@ZIF-8 are as follows: diluting a HAuCl4·3H2O solution with deionized water, adding MPA and NaOH solutions, and stirring the mixture at room temperature for 0.5 to 1.5 hours to obtain a MPA-AuNCs solution; adding the MPA-AuNCs solution to a zinc nitrate (Zn[NO3]2) aqueous solution, ultrasonically dispersing for 20 to 40 minutes, then adding a 2-methylimidazole (2-MeIm) aqueous solution, vigorously stirring the mixture for 22 to 26 hours, centrifuging, washing the precipitate with methanol, and drying in a vacuum at 50 to 70° C. to obtain the MPA-AuNCs solution; The preparation steps of the (2-mercaptobenzoic acid)-gold nanocluster@zeolite imidazole framework material ([2-MBA]-AuNCs@ZIF-8) are as follows: dissolving 2-MBA in deionized water, adding a NaOH solution, then adding a HAuCl4·3H2O solution and mixing evenly, and stirring at 20 to 30°C for 6 to 10 hours to obtain a (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution; adding the (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution to a zinc nitrate (Zn[NO3]2) aqueous solution, ultrasonically dispersing for 20 to 40 minutes, then adding a 2-methylimidazole (2-MeIm) aqueous solution, vigorously stirring the mixture for 22 to 26 hours, centrifuging, washing the precipitate with methanol, and drying in a vacuum at 50 to 70°C to obtain the obtained product.

2. The method according to claim 1, characterized in that The preparation steps of glutathione-gold nanocluster@zeolite imidazolate framework material (GSH-AuNCs@ZIF-8) are as follows: HAuCl4·3H2O solution and GSH solution are added to deionized water and mixed evenly, stirred at 500 rpm at 70°C for 24 hours to obtain glutathione-gold nanocluster (GSH-AuNCs) solution, the glutathione-gold nanocluster (GSH-AuNCs) solution is added to zinc nitrate (Zn[NO3]2) aqueous solution, ultrasonically dispersed for 30 minutes, and then 2-methylimidazole (2-MeIm) aqueous solution is added, the mixture is vigorously stirred for 24 hours, centrifuged, the precipitate is washed three times with methanol, and dried in a vacuum at 60°C for 8 hours.

3. The method according to claim 1, characterized in that The preparation steps of mercaptopropionic acid-gold nanoclusters@zeolite imidazolate framework material (MPA-AuNCs@ZIF-8) are as follows: dilute HAuCl4·3H2O solution with deionized water, then add MPA and NaOH solutions, stir the mixture at room temperature for 1 hour to obtain mercaptopropionic acid-gold nanoclusters (MPA-AuNCs) solution; add mercaptopropionic acid-gold nanoclusters (MPA-AuNCs) solution into zinc nitrate (Zn[NO3]2) aqueous solution, ultrasonically disperse for 30 minutes, then add 2-methylimidazole (2-MeIm) aqueous solution, stir the mixture vigorously for 24 hours, centrifuge, wash the precipitate with methanol three times, and dry it in a vacuum at 60°C for 8 hours.

4. The method according to claim 1, characterized in that The preparation steps of the (2-mercaptobenzoic acid)-gold nanocluster@zeolite imidazole framework material ([2-MBA]-AuNCs@ZIF-8) are as follows: dissolve 2-MBA in deionized water, add NaOH solution, then add HAuCl4·3H2O solution and mix evenly, and stir at 25°C for 8 hours to obtain a (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution; add the (2-mercaptobenzoic acid)-gold nanocluster ([2-MBA]-AuNCs) solution to a zinc nitrate (Zn[NO3]2) aqueous solution, ultrasonically disperse for 30 minutes, then add a 2-methylimidazole (2-MeIm) aqueous solution, vigorously stir the mixture for 24 hours, centrifuge, wash the precipitate with methanol three times, and dry it in a vacuum at 60°C for 8 hours.

5. The method according to any one of claims 1 to 4, characterized in that: The ratio of zinc nitrate (Zn[NO3]2), 2-methylimidazole (2-MeIm) and deionized water is maintained at 1:50-70:1100-1200, in mass percentage.

6. The method according to claim 5, characterized in that The ratio of zinc nitrate (Zn[NO3]2), 2-methylimidazole (2-MeIm) and deionized water is maintained at 1:60:1150, calculated in mass percentage.

7. The method according to any one of claims 1 to 6, characterized in that: The aggregation-induced enhanced fluorescence sensor array is constructed by adding solutions of three sensor elements and heavy metal ion solution into a centrifuge tube, incubating the mixed solution at 20-30° C. for 30-50 minutes, and then detecting the fluorescence intensity of the system by an ELISA instrument to obtain a training data matrix.

8. The method according to claim 7, characterized in that The aggregation-induced enhanced fluorescence sensor array is constructed as follows: solutions of three sensor element materials, heavy metal ion solution, and buffer solution are added to a centrifuge tube in sequence, the mixed solution is incubated at 25° C. for 40 minutes, and then the fluorescence intensity of the system is detected by an ELISA instrument to obtain a training data matrix of 3 sensor elements×8 heavy metal ions×5 repetitions.

9. The method according to claim 8, characterized in that The solutions of the three sensor element materials are added at a concentration of 0.1 mg / mL and a volume of 50 μL; the heavy metal ion solution is added at a volume of 50 μL; and the Tris-HCl buffer or HEPES buffer is added at a volume of 900 μL.

10. The method according to any one of claims 1 to 9, characterized in that: The data processing is to use the software SPSSStatistics 27 to process the obtained data, obtain the unique spectral fingerprint data of each heavy metal ion, accurately distinguish and quantify eight heavy metal ions; the eight heavy metal ions are Ni 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2+ 、Ag + , Cu 2+ and Zn 2 + .

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