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

Abstract

The present invention provides a method for detecting heavy metal ions based on an 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 a coordination reaction. The different degrees of fluorescence intensity regulation of the three sensor elements by heavy metal ions are used as output signals. Linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA) are used to obtain unique spectral fingerprint data for each heavy metal ion. A database for identifying eight heavy metal ions is successfully established. The obtained data is then processed using the software SPSS Statistics 27 to obtain unique spectral fingerprint data for each heavy metal ion, thereby realizing the identification of eight heavy metal ions (Ni 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2+ 、Ag + 、Cu 2+ and Zn 2+ ) for precise identification and sensitive quantitative detection.

Description

Technical Field

[0001] The present invention relates to the field of heavy metal ion detection in water environments, 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 during industrial activities are generally difficult to biodegrade, and thus pose a threat to human health through the food chain. Therefore, accurate quantification of multiple heavy metal ions in complex environments is crucial for environmental protection and human health. Several currently established instrumental methods, such as X-ray fluorescence spectrometry (XRF), atomic absorption spectrometry (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 generate a unique "fingerprint" for each analyte. Intelligent data classification using linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA) yields this "fingerprint" information, enabling the discrimination of multiple analytes. The recognition element, as the cornerstone of the sensor array's analytical performance, is crucial. Among these sensing elements, gold nanoclusters (AuNCs) stand out due to their unique optical properties and programmable surface ligands. However, because the luminescence efficiency of AuNCs is affected by the vibration and spin of their intramolecular ligands, nanocluster-based sensor arrays suffer from low fluorescence quantum yields and weak analytical performance. Numerous efforts have been made to improve the luminescence efficiency of AuNCs. For example, in situ selective doping of AuNCs with silver atoms improves luminescence efficiency by reducing non-radiative losses. However, noble metal doping increases experimental costs and also limits luminescence efficiency. Summary of the Invention

[0004] In order to solve the problems in the prior art, the present invention provides a method for detecting heavy metal ions based on an 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 a coordination reaction. The different degrees of fluorescence intensity regulation of the three sensor elements by heavy metal ions are used as output signals. Linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA) are used to obtain unique spectral fingerprint data for each heavy metal ion. A database for identifying eight heavy metal ions is successfully established. The obtained data is then processed using SPSS Statistics 27 software to obtain unique spectral fingerprint data for each heavy metal ion, thereby realizing the identification of eight heavy metal ions (Ni 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2+ 、Ag + 、Cu 2+ and Zn 2+ ) for precise 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 (AIE) sensor array includes the preparation of three sensor elements, the construction of an AIE 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] HAuCl4·3H2O solution and GSH solution are added to deionized water and mixed, and stirred at 300-600 rpm at 60-80°C for 22-26 hours 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 and ultrasonically dispersed for 20-40 minutes, followed by the addition of a 2-methylimidazole (2-MeIm) aqueous solution, and the mixture is vigorously stirred for 22-26 hours, centrifuged, and the precipitate is washed with methanol and dried in a vacuum at 50-70°C.

[0009] Specifically, the preparation steps of glutathione-gold nanoclusters@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, and stirred at 500 rpm at 70°C for 24 hours to obtain glutathione-gold nanoclusters (GSH-AuNCs) solution; the glutathione-gold nanoclusters (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 and centrifuged. The precipitate is 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 nanoclusters@zeolite imidazolate framework material (MPA-AuNCs@ZIF-8) are as follows:

[0011] A HAuCl4·3H2O solution was diluted with deionized water, and MPA and NaOH solutions were added. The mixture was stirred at room temperature for 0.5 to 1.5 hours to obtain a mercaptopropionic acid-gold nanoclusters (MPA-AuNCs) solution. The mercaptopropionic acid-gold nanoclusters (MPA-AuNCs) solution was added to a zinc nitrate (Zn[NO3]2) aqueous solution and ultrasonically dispersed for 20 to 40 minutes. Subsequently, a 2-methylimidazole (2-MeIm) aqueous solution was added, and the mixture was vigorously stirred for 22 to 26 hours. The mixture was centrifuged and the precipitate was washed with methanol and dried 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 HAuCl4·3H2O solution with deionized water, then add MPA and NaOH solutions, and stir the mixture at room temperature for 1 hour to obtain mercaptopropionic acid-gold nanoclusters (MPA-AuNCs) solution; add the mercaptopropionic acid-gold nanoclusters (MPA-AuNCs) solution to zinc nitrate (Zn[NO3]2) aqueous solution, ultrasonically disperse for 30 minutes, and 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.

[0013] The preparation steps of the (2-mercaptobenzoic acid)-gold nanocluster@zeolite imidazolate 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, mixing evenly, and stirring at 20-30°C for 6-10 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 20-40 minutes, then adding a 2-methylimidazole (2-MeIm) aqueous solution, vigorously stirring the mixture for 22-26 hours, centrifuging, washing the precipitate with methanol, and drying in a vacuum at 50-70°C to obtain the obtained product.

[0014] Specifically, the preparation steps of (2-mercaptobenzoic acid)-gold nanoclusters@zeolite imidazolate 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 (2-mercaptobenzoic acid)-gold nanoclusters ([2-MBA]-AuNCs) solution; add (2-mercaptobenzoic acid)-gold nanoclusters ([2-MBA]-AuNCs) solution to zinc nitrate (Zn[NO3]2) aqueous solution, ultrasonically disperse for 30 minutes, and 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.

[0015] According to one embodiment of the present invention, the ratio of zinc nitrate (Zn[NO3]2), 2-methylimidazole (2-MeIm), and deionized water is maintained at 1:50-70:1100-1200, calculated as a mass percentage. Furthermore, the ratio of zinc nitrate (Zn[NO3]2), 2-methylimidazole (2-MeIm), and deionized water is maintained at 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 enzyme-labeled 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 a microplate reader 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 at a volume of 50 μL; and the Tris-HCl buffer or HEPES buffer is added at 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 distinguishing and quantifying 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] This invention pioneered the development of three gold nanoclusters and zeolite imidazolate framework materials as sensing elements, constructing an aggregation-induced enhanced fluorescence (AIEF) sensor array. Due to the varying binding effects between the eight heavy metal ions and the three sensing elements, the fluorescence intensity of the gold nanoclusters and zeolite imidazolate framework materials was modulated to varying degrees. Further analysis using statistical methods allowed for the differentiation of the heavy metal ions. This sensor array can accurately identify the eight heavy metal ions within a concentration range of 0.5 to 50 μM, and can also identify multi-component mixtures of heavy metal ions. It demonstrates excellent discrimination not only in tap water but also in complex samples of traditional Chinese medicine, such as astragalus and angelica, and possesses significant application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 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 This is a fingerprint spectrum formed by the recognition results of the sensor array of the present invention for eight heavy metal ions.

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

[0025] Figure 4 3D typical scoring diagrams 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 Detection results of the sensor array of the present invention on 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 with reference to 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 at zeolite imidazolate framework (GSH-AuNCs@ZIF-8): HAuCl₄·3H₂O solution (0.5 mL, 20 mM) and GSH solution (0.15 mL, 100 mM) were mixed in 4.35 mL of deionized water. The resulting mixture was stirred at 500 rpm at 70°C for 24 hours to obtain a glutathione-gold nanocluster (GSH-AuNCs) solution. The GSH-AuNCs solution was then added to an aqueous zinc nitrate (Zn[NO₃]₂) solution and ultrasonically dispersed for 30 minutes. Subsequently, an aqueous 2-methylimidazole (2-MeIm) solution was added. The ratio of zinc nitrate (Zn[NO₃]₂), 2-methylimidazole (2-MeIm), and deionized water was maintained at approximately 1:60:1150. Finally, the mixture was vigorously stirred for 24 h, centrifuged, washed three times with methanol, and dried in vacuo at 60 °C for 8 h.

[0030] Preparation of mercaptopropionic acid-gold nanoclusters@zeolitic imidazolate framework (MPA-AuNCs@ZIF-8): HAuCl4·3H2O solution (0.8 mL, 20 mM) was diluted with 68.64 mL of deionized water, followed by the addition of MPA (9.6 mL, 10 mM) and NaOH solution (0.96 mL, 100 mM). The mixture was stirred at room temperature for 1 h to obtain a mercaptopropionic acid-gold nanocluster (MPA-AuNCs) solution. The MPA-AuNCs solution was then added to an aqueous zinc nitrate (Zn[NO3]2) solution and ultrasonically dispersed for 30 min. Subsequently, an aqueous 2-methylimidazole (2-MeIm) solution was added. The ratio of zinc nitrate (Zn[NO3]2), 2-methylimidazole (2-MeIm), and deionized water was maintained at approximately 1:60:1150. Finally, the mixture was vigorously stirred for 24 h, centrifuged, washed three times with methanol, and dried in vacuo at 60 °C for 8 h.

[0031] (2-Mercaptobenzoic acid)-gold nanoclusters@zeolitic imidazolate framework ([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 obtain a 50 mM 2-MBA solution. HAuCl₄·3H₂O solution (4 mL, 20 mM) was mixed into the solution and stirred at 25°C for 8 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 to an aqueous zinc nitrate (Zn[NO₃]₂) solution and ultrasonically dispersed for 30 minutes. Subsequently, an aqueous 2-methylimidazole (2-MeIm) solution was added. The ratio of zinc nitrate (Zn[NO3]2), 2-methylimidazole (2-MeIm) and deionized water was maintained at approximately 1:60:1150. Finally, the mixture was vigorously stirred for 24 h, centrifuged, washed three times with methanol, and dried in a vacuum at 60 °C for 8 h.

[0032] 2. 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 its maximum at the excitation wavelength of 290 nm and the emission wavelength of 581 nm. Figure 1 As shown in Figure C, (2-MBA)-AuNCs@ZIF-8 has a maximum fluorescence intensity at an excitation wavelength of 323 nm and an emission wavelength of 640 nm.

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

[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: 10 μM). Add 50 μL of the gold nanocluster@zeolitic imidazolate framework solution, 50 μL of the heavy metal ion solution, and 900 μL of either Tris-HCl buffer or HEPES buffer to each centrifuge tube. Incubate at 25°C for 40 minutes. The fluorescence intensity of the three sensor elements after the addition of the heavy metal ions is measured at the selected wavelength. Different heavy metal ions exhibit varying effects on the fluorescence intensity of different sensor elements.

[0036] Detection of eight heavy metal ions using aggregation-induced enhanced fluorescence sensor array: Preparation of Ni with different concentrations 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2+ 、Ag + 、Cu 2+ and Zn 2+ Aqueous solutions (final concentrations of 50 μM, 10 μM, 1 μM, and 0.5 μM, respectively) were added to centrifuge tubes. 50 μL of the gold nanocluster@zeolite imidazolate framework solution, 50 μL of the heavy metal ion solution, and 900 μL of Tris-HCl buffer or HEPES buffer were added, respectively. The mixture was incubated at 25°C for 40 minutes, and the test was repeated five times. The excitation and emission wavelengths were set in a microplate reader, and the fluorescence intensity of the three sensor elements after the addition of heavy metal ions was measured. The resulting training data matrix consisted of 3 sensor elements × 8 heavy metal ions × 5 repetitions.

[0037] Detection of heavy metal ion mixtures using aggregation-induced enhanced fluorescence sensor array: 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+ To each centrifuge tube, add 50 μL of the gold nanocluster@zeolitic imidazolate framework solution, 50 μL of the heavy metal ion solution, and 900 μL of either Tris-HCl buffer or HEPES buffer. Mix and incubate at 25°C for 40 minutes. Repeat the test five times. Set the excitation and emission wavelengths on a microplate reader and measure the fluorescence intensity of the three sensor elements after the addition of heavy metal ions.

[0038] Detection of heavy metal ions in actual samples using an aggregation-induced enhanced fluorescence sensor array: 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 (Ni 2+ Cr 2+ 、Co 2+ , Pb 2+ 、Cd 2+ 、Ag + 、Cu 2+ and Zn 2+ To each centrifuge tube, add 50 μL of the gold nanocluster@zeolitic imidazolate framework solution, 50 μL of the heavy metal ion solution, and 900 μL of either Tris-HCl buffer or HEPES buffer. Mix and incubate at 25°C for 40 minutes. Repeat the experiment five times. Set the excitation and emission wavelengths on a microplate reader and measure the fluorescence intensity of the three sensor elements after the addition of heavy metal ions. This results in a training data matrix consisting of 3 sensor elements, 8 heavy metal ions, and 5 replicates.

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

[0040] Aggregation-induced enhanced fluorescence sensor array was used to detect eight heavy metal ions: four final concentration training data matrices (3 sensor elements × 8 heavy metal ions × 5 repetitions) were processed by 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, as shown in 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, as shown in 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, as shown in Figure 2As shown in D, in the LDA two-dimensional score graph, 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 array: 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 software, as shown in Figure 2. Figure 5 As shown in the LDA score diagram, the eight heavy metal ions are well distinguished. Figure 5 As shown in A, factor 1 and factor 2 are 90.3% and 7.7% respectively; for heavy metal ions in the precipitate of Astragalus sample, Figure 5 As shown in B, factors 1 and 2 are 97.6% and 1.4% respectively; for heavy metal ions in the precipitate of Angelica sinensis sample, Figure 5 As shown in Figure C, factors 1 and 2 are 77.7% and 13.8%, respectively, which further demonstrates that the constructed aggregation-induced enhanced fluorescence sensor array is capable of distinguishing heavy metal ions in complex environments.

Claims

1. A method for heavy metal ion detection based on an aggregation-induced enhanced fluorescence (AIE) sensor array, comprising the preparation of three sensor elements: glutathione-gold nanoclusters@zeolite imidazolate framework (GSH-AuNCs@ZIF-8), mercaptopropionic acid-gold nanoclusters@zeolite imidazolate framework (MPA-AuNCs@ZIF-8), and 2-mercaptobenzoic acid-gold nanoclusters@zeolite imidazolate framework ([2-MBA]-AuNCs@ZIF-8). The preparation steps of the 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, mixed, and stirred at 300-600 rpm at 60-80°C for 22-26 hours to obtain a glutathione-gold nanocluster GSH-AuNCs solution; the glutathione-gold nanocluster GSH-AuNCs solution is added to a zinc nitrate aqueous solution, ultrasonically dispersed for 20-40 minutes, and then a 2-methylimidazole aqueous solution is added. The mixture is vigorously stirred for 22-26 hours, centrifuged, and the precipitate is washed with methanol and dried in a vacuum at 50-70°C. The preparation steps of the MPA-AuNCs@ZIF-8 are as follows: diluting HAuCl4·3H2O solution with deionized water, adding MPA and NaOH solution, and stirring the mixture at room temperature for 0.5-1.5 hours to obtain a mercaptopropionic acid-gold nanocluster MPA-AuNCs solution; The MPA-AuNCs solution was added to an aqueous zinc nitrate solution and ultrasonically dispersed for 20-40 min. Then, an aqueous 2-methylimidazole solution was added. The mixture was vigorously stirred for 22-26 h and centrifuged. The precipitate was washed with methanol and dried in a vacuum at 50-70 °C. The preparation steps of the [2-MBA]-AuNCs@ZIF-8 are as follows: dissolving 2-MBA in deionized water, adding NaOH solution, then adding HAuCl4·3H2O solution, mixing evenly, and stirring at 20-30°C for 6-10 hours to obtain a (2-mercaptobenzoic acid)-gold nanocluster [2-MBA]-AuNCs solution; The [2-MBA]-AuNCs solution was added to an aqueous zinc nitrate solution and ultrasonically dispersed for 20-40 min. Then, an aqueous 2-methylimidazole solution was added. The mixture was vigorously stirred for 22-26 h and centrifuged. The precipitate was washed with methanol and dried in a vacuum at 50-70 °C. The aggregation-induced enhanced fluorescence sensor array is constructed by adding solutions of three sensor elements and a 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 with a microplate reader to obtain a training data matrix; The data were processed using SPSS Statistics 27 software to obtain unique spectral fingerprint data for each heavy metal ion, accurately distinguishing and quantifying 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+ .

2. The method according to claim 1, wherein The preparation steps of GSH-AuNCs@ZIF-8 are as follows: HAuCl4·3H2O solution and GSH solution are added to deionized water and mixed evenly. The mixture is stirred at 500 rpm at 70°C for 24 hours to obtain a GSH-AuNCs solution. The GSH-AuNCs solution is then added to an aqueous zinc nitrate solution and ultrasonically dispersed for 30 minutes. Subsequently, an aqueous 2-methylimidazole solution is added, and the mixture is vigorously stirred for 24 hours. The mixture is centrifuged and 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, wherein The preparation steps of MPA-AuNCs@ZIF-8 were as follows: HAuCl4·3H2O solution was diluted with deionized water, followed by addition of MPA and NaOH solution, and the mixture was stirred at room temperature for 1 h to obtain MPA-AuNCs solution; The MPA-AuNCs solution was added to a zinc nitrate aqueous solution and ultrasonically dispersed for 30 min. Subsequently, a 2-methylimidazole aqueous solution was added, and the mixture was vigorously stirred for 24 h. After centrifugation, the precipitate was washed three times with methanol and dried in a vacuum at 60°C for 8 h.

4. The method according to claim 1, wherein The preparation steps of the [2-MBA]-AuNCs@ZIF-8 are as follows: dissolving 2-MBA in deionized water, adding NaOH solution, then adding HAuCl4·3H2O solution, mixing evenly, and stirring at 25°C for 8 hours to obtain a [2-MBA]-AuNCs solution; The [2-MBA]-AuNCs solution was added to a zinc nitrate aqueous solution and ultrasonically dispersed for 30 min. Subsequently, a 2-methylimidazole aqueous solution was added, and the mixture was vigorously stirred for 24 h. After centrifugation, the precipitate was washed three times with methanol and dried in a vacuum at 60°C for 8 h.

5. The method according to any one of claims 1 to 4, characterized in that The ratio of the zinc nitrate, 2-methylimidazole and deionized water is maintained at 1:50-70:1100-1200, calculated in mass percentage.

6. The method according to claim 5, wherein The ratio of zinc nitrate, 2-methylimidazole and deionized water is maintained at 1:60:1150, in mass percentage.

7. The method according to claim 1, wherein The aggregation-induced enhanced fluorescence sensor array was constructed as follows: solutions of three sensor element materials, a heavy metal ion solution, and a buffer solution were sequentially added to a centrifuge tube, the mixed solution was incubated at 25°C for 40 minutes, and the fluorescence intensity of the system was then detected by a microplate reader to obtain a training data matrix of 3 sensor elements × 8 heavy metal ions × 5 repetitions.

8. The method according to claim 7, wherein 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 buffer is Tris-HCl buffer or HEPES buffer, and the volume is added at 900 μL.

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