Electrochemiluminescence perovskite quantum dot probe with stable aqueous phase and preparation method and application thereof

Abstract

The invention discloses an electrochemiluminescence perovskite quantum dot probe with a stable water phase and a preparation method and application thereof. Aiming at the technical bottleneck that the existing perovskite quantum dots are unstable in a water phase and are difficult to be directly used for liquid phase detection, the invention provides a method for preparing an oleylamine / trifluoropropionic acid (OAm / TFPro) double-ligand protected perovskite quantum dot (PQDs) probe by adopting a water phase co-deposition method. The TFPro ligand and water molecules form a hydrogen bond interface through a fluorine-containing group of the TFPro ligand, and a protective layer is constructed on the surfaces of the PQDs, so that the PQDs can be stably dispersed in a water phase for a long time, and efficient electrochemical luminescence (ECL) activity is maintained. An ECL sensing platform constructed based on the probe realizes high-sensitivity and high-selectivity detection of tea polyphenol in tea leaves, and has the advantages of wide linear range, low detection limit, strong anti-interference capability and the like. The method is simple in process and low in cost, and a novel efficient detection tool is provided for the field of food quality safety.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials and analytical detection technology, specifically relating to an aqueous phase-stable electrochemiluminescent perovskite quantum dot probe, its preparation method, and its application. Background Technology

[0002] Tea polyphenols (TPPs) in tea are the core active ingredients that determine the quality and health benefits of tea, possessing significant antioxidant, anti-inflammatory, anti-cancer, and cardiovascular disease prevention functions. However, the intake of tea polyphenols needs to be controlled within a reasonable range, as excessive intake may cause adverse reactions. Therefore, establishing rapid, sensitive, and accurate methods for detecting tea polyphenols is of great significance for tea quality control, functional food development, and food safety supervision.

[0003] Currently, the main methods for detecting tea polyphenols include high-performance liquid chromatography (HPLC), spectrophotometry, and electrochemical methods. These methods either rely on expensive, large-scale instruments, are complex and time-consuming to operate, or suffer from insufficient sensitivity and selectivity. In recent years, nanomaterial-based sensing technologies have attracted widespread attention due to their high sensitivity and potential portability. Among them, perovskite quantum dots (PQDs), with their excellent optical properties, high fluorescence quantum yield, and tunable emission wavelength, are considered ideal materials for next-generation high-performance luminescent probes, demonstrating great potential in the fields of optoelectronics and sensing.

[0004] However, applying PQDs to aqueous systems, especially for the direct detection of complex samples such as food and biological samples, faces a fundamental technical bottleneck: PQDs prepared by traditional methods (especially organic-inorganic hybrid perovskites) are extremely unstable in polar solvents such as water and alcohols, and their crystal structure degrades rapidly, leading to luminescence quenching, which severely limits their practical application in liquid phase analysis. Although some studies have attempted to improve the stability of PQDs through surface ligand engineering or coating strategies, these often suffer from problems such as complex preparation processes, loss of luminescence efficiency, or difficulties in functionalization. In addition, existing novel sensing materials for tea polyphenol detection (such as the protein-template-based metal nanoclusters disclosed in Chinese patent application CN115673311A, and the organic small molecule probes based on borate ester reactions disclosed in Chinese patent applications CN114085241A and CN116559157A) have their own characteristics, but their sensitivity, stability, or anti-interference ability still have room for improvement, and none of them involve the technical path of constructing an ECL sensing platform using high-performance PQDs.

[0005] Therefore, developing a PQDs probe that can exist stably in the aqueous phase while maintaining efficient ECL luminescence performance, and establishing a new method for detecting tea polyphenols with high sensitivity and selectivity based on this, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an aqueous-phase stable electrochemiluminescent perovskite quantum dot probe, its preparation method, and its application. It is the first to develop an aqueous-phase stable perovskite quantum dot electrochemiluminescent probe based on dual-ligand protection, achieving highly sensitive and selective detection of tea polyphenols in tea.

[0007] This invention is achieved through the following technical solution:

[0008] A method for preparing an aqueous-phase stable electrochemiluminescent perovskite quantum dot probe includes the following steps:

[0009] Step 1) PbBr2, CsBr and 2-methylimidazole are dissolved in N,N-dimethylacetamide and stirred at 60°C; then oleylamine and trifluoropropionic acid are added to the reaction system simultaneously and the reaction is continued at 60°C.

[0010] Step 2) The reaction solution obtained in step 1) is injected into ethyl acetate, allowed to stand at 60°C to crystallize, the precipitate is collected by centrifugation, and then ultrasonically dispersed in the aqueous phase to obtain an aqueous phase-stable OAm / TFPro dual-ligand protected PQDs probe.

[0011] Preferably, in step 1), the amount of PbBr2 is 146.8 mg; the amount of CsBr is 85.1 mg; the amount of 2-methylimidazole is 8.2 mg; the amount of N,N-dimethylacetamide is 10 mL; the amount of oleylamine is 500 μL; and the amount of trifluoropropionic acid is 300 μL.

[0012] The PQDs probes prepared by the above method contain a composite crystal form of CsPbBr3 and CsPb2Br5, and their surfaces are jointly modified by OAm and TFPro. They can be stably dispersed in the aqueous phase for a long time and maintain high ECL luminescence efficiency.

[0013] Preferably, the TFPro forms a hydrogen bond interface between fluorine atoms and water molecules, preventing water molecules from penetrating into the PQDs core, thereby allowing the PQDs to maintain their structural and luminescent stability in the aqueous phase.

[0014] The above-mentioned PQD probes are used in the preparation of sensors or detection kits for detecting tea polyphenols.

[0015] An ECL sensing platform for detecting tea polyphenols includes:

[0016] First, the above-mentioned PQDs probe dispersion was coated on the surface of the working electrode to prepare a modified electrode; then, the modified electrode, the reference electrode, and the counter electrode were combined to form a three-electrode system, which was placed in a PBS buffer containing K2S2O8 and the analyte for ECL signal acquisition.

[0017] Preferably, the potential scanning range of the ECL signal acquisition is 0V to -2.2V, the scanning rate is 100 mV / s, and the photomultiplier tube voltage is 600V.

[0018] A method for detecting tea polyphenols in tea leaves, using the aforementioned PQDs probe, quantitatively detects tea polyphenols by measuring the degree of quenching of its electrochemiluminescence signal.

[0019] Preferably, the linear range for the detection of tea polyphenols is from 0.0001 μg / mL to 500 μg / mL.

[0020] Preferably, the method exhibits high selectivity for tea polyphenols, and common interfering substances include histidine, theophylline, theanine, cysteine, glucose, fructose, sucrose, and Hg. 2+ Ag + Fe 2+ Al 3+ Ca 2+ K + Mg 2+ Cu 2+ Zn 2+ NO3 - Cl - SO4 2- .

[0021] The beneficial effects of this invention are as follows:

[0022] (1) This invention innovatively employs an aqueous co-deposition method and introduces a synergistic protection strategy using oleylamine (OAm) and trifluoropropionic acid (TFPro) dual ligands. The surface of the prepared OAM / TFPro PQDs probe is surrounded by a large number of OAM and TFPro ligands, and is protected by Pb. 2 + -N and Pb 2+ -O coordination bonds fix the PQDs probe surface, which facilitates the formation of a dynamic hydrogen bond network between the fluorinated end groups of the TFPro ligands and surrounding water molecules, constructing a "water molecule protective interface" on the PQDs surface. This effectively blocks the direct erosion of water molecules, thereby achieving long-term stable dispersion and storage of PQDs in the aqueous phase, breaking through the key technical bottleneck that traditional PQDs cannot be directly applied to aqueous phase detection.

[0023] (2) Thanks to its unique stabilization structure, the OAm / TFPro PQDs prepared in this invention are not only stable in aqueous phase, but also exhibit significantly enhanced and stable ECL performance. Compared with PQDs protected by a single ligand, their ECL signal intensity is greatly improved, and they show good stability under different pH environments and continuous scanning, laying a material foundation for building a high signal-to-noise ratio ECL sensing platform.

[0024] (3) The ECL sensing platform constructed based on the aqueous stable PQDs probe of this invention exhibits excellent response performance to tea polyphenols. The detection linear range is wide, from 0.0001 μg / mL to 500 μg / mL, covering the possible concentration range of tea polyphenols in actual samples. The detection limit is extremely low, meeting the requirements of trace analysis.

[0025] (4) The ECL sensing platform of the present invention can detect common coexisting substances in tea, such as various amino acids (histidine, theanine, cysteine), alkaloids (theophylline), and metal ions (Hg). 2+ Ag + Zn 2+ ) and anions (NO3) - Cl - SO4 2- These all exhibit extremely low response signals, but show significant responses to tea polyphenols, demonstrating high specificity and selectivity. They are suitable for analysis of complex matrices (such as tea extracts) after direct or simple processing.

[0026] (5) The entire probe of this invention is synthesized using a one-step aqueous co-deposition method, which does not require complex post-processing or secondary encapsulation. The reaction conditions are mild (60°C) and the raw materials are readily available. The construction and detection process of the sensing platform is simple to operate and does not require expensive instruments. It provides the possibility for rapid on-site detection or high-throughput screening of tea polyphenols, and has good prospects for industrial application. It has important application value in the fields of food analysis and environmental monitoring. Attached Figure Description

[0027] Figure 1 The images show the TEM image (a) and elemental analysis mapping image (bi) of the OAm / TFPro PQDs in Example 1.

[0028] Figure 2 The XRD patterns (a) and FT-IR spectra (b) of OAm PQDs and OAm / TFPro PQDs in Example 1 are shown.

[0029] Figure 3 Comparison of continuous ECL signals of OAm PQDs and OAm / TFPro PQDs in pH 7.4 PBS buffer in Example 1;

[0030] Figure 4 The following are performance graphs of the ECL sensing platform based on OAm / TFPro PQDs in Example 2 for detecting TPPs: a is the ECL signal response graph under different concentrations of TPPs; b is the standard curve for TPPs detection plotted based on the degree of ECL signal quenching.

[0031] Figure 5 This study focuses on the selectivity of the ECL sensing platform based on OAm / TFPro PQDs in Example 3.

[0032] Figure 6 ECL stability study of OAm / TFPro PQDs in Example 4. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0034] Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art, and the experimental methods without specific conditions are all conventional methods in the art.

[0035] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0036] Example 1: Preparation and Characterization of OAm / TFPro PQDs Probes

[0037] 1. Preparation of OAm / TFPro PQDs probes

[0038] A method for preparing an aqueous-phase stable electrochemiluminescent perovskite quantum dot probe, the specific steps of which are as follows:

[0039] (1) Weigh 146.8 mg PbBr2, 85.1 mg CsBr and 8.2 mg 2-methylimidazole (2-Met) and add them sequentially into a three-necked flask containing 10 mL N,N-dimethylacetamide (DMA). Then stir the mixture at 60 °C for 60 min.

[0040] (2) Subsequently, 500 μL of oleylamine (OAm) and 300 μL of trifluoropropionic acid (TFPro) were added to the above reaction system simultaneously using a pipette, and the reaction was continued at 60°C for 60 min.

[0041] (3) After the reaction is complete, take 3.0 mL of the above reaction solution and quickly inject it into 30 mL of ethyl acetate (EA) and mix it quickly. Then place it at 60°C and let it stand for 60 min to ensure that the material is completely crystallized.

[0042] (4) Centrifuge the above mixture at 5000 rpm for 10 min, discard the supernatant, and collect the orange precipitate at the bottom of the centrifuge tube. Add 2 mL of ultrapure water to the precipitate and sonicate it to dissolve it completely. Finally, a clear orange aqueous dispersion is obtained, which is the OAm / TFPro PQDs probe precursor solution. Store it in a refrigerator at 4℃ for later use.

[0043] Meanwhile, OAm PQDs were set up as a control experiment. The preparation method was the same as that of OAm / TFPro PQDs probes, except that only 500 μL of OAm was added in step (2), and TFPro was not added. After preparation, it was also stored in a refrigerator at 4°C for later use.

[0044] 2. Characterization of OAm / TFPro PQDs probes

[0045] The morphology of the prepared OAm / TFPro PQDs probes was characterized as follows: Figure 1 As shown in Figure a, transmission electron microscopy (TEM) reveals that PQDs exhibit a square or rectangular shape. High-power transmission electron microscopy (HRTEM) indicates that PQDs possess the (021) crystal plane of CsPbBr3 and the (002) crystal plane of CsPb2Br5. Figure 1 (Inset a, inner illustration) shows that the synthesized PQDs have two crystal forms: CsPbBr3 and CsPb2Br5.

[0046] The structural composition of the OAm / TFPro PQDs probe was further characterized by XRD, such as... Figure 2 As shown in Figure a, the results are consistent with the HRTEM results, indicating that the prepared PQDs probe is composed of two crystal forms, CsPbBr3 and CsPb2Br5.

[0047] The elemental composition of the OAm / TFPro PQDs probes was characterized using TEM mapping, such as... Figure 1 As shown in Figure bi, the synthesized PQDs probe is composed of seven elements: Cs, Pb, Br, F, C, N, and O.

[0048] The surface state of the OAm / TFPro PQDs probe was characterized by Fourier transform infrared spectroscopy (FT-IR), such as... Figure 2 As shown in Figure b, the spectral results demonstrate that the two ligands are successfully anchored to the surface of PQDs via covalent bonding.

[0049] The aqueous ECL properties of the OAm / TFPro PQDs probe material were investigated, and the results are as follows: Figure 3As shown, compared with the ECL performance of OAm PQDs without the participation of TFPro ligand protection, PQDs protected by both OAm and TFPro ligands have high ECL luminous efficiency and very stable ECL intensity, which fully demonstrates the importance of TFPro ligand in regulating the photophysical properties of PQDs.

[0050] In this embodiment, OAm / TFPro PQDs nanoprobes were prepared using an aqueous co-deposition method. The reaction solution was acidic (since trifluoropropionic acid is acidic itself, its addition to the reaction system would make the system acidic, with an estimated pH of approximately 2). This allowed for the protonation of the amino groups of OAm, thus enabling more TFPro ligands to bind with Pb. 2+ Ion bonding forms OAm and TFPro dual ligands to protect PQDs. Because the surface of PQDs contains a large number of fluorine-containing TFPro ligands, fluorine atoms can be trapped on the surface by hydrogen bonding with external water molecules to form a water molecule protective interface, thereby enabling PQDs nanomaterials to be uniformly and stably dispersed in the aqueous phase.

[0051] Example 2: Detection of TPPs based on OAm / TFPro PQDs probes

[0052] 1. Preparation of ECL working electrode

[0053] The OAM / TFPro PQDs precursor solution prepared in Example 1 was diluted 10 times, and then 6.0 μL of the diluted OAM / TFPro PQDs was drop-coated onto the surface of a polished glassy carbon electrode (GCE). The electrode was then allowed to dry naturally at room temperature to obtain the OAM / TFPro PQDs modified working electrode.

[0054] 2. ECL detection and standard curve establishment of TPPs

[0055] The working electrode, reference electrode (Ag / AgCl), and counter electrode (Pt wire) prepared above were inserted together into a PBS buffer (0.1 M, pH 7.4) containing 0.1 M K₂S₂O₈ and different concentrations of TPPs to form a three-electrode system. The potential scan range was set to 0 V to -2.2 V, the scan rate to 100 mV / s, and the photomultiplier tube voltage to 600 V, and the ECL signal was recorded.

[0056] The TPP concentration gradient was set to: 0.0001, 0.001, 0.01, 0.1, 1, 10, 100, 500, 1000 μg / mL. The quenching efficiency ([(ECL0-ECL) / ECL0]) was calculated using the ECL signal without TPPs as ECL0 and the signal with TPPs as ECL. A plot of the quenching efficiency against the logarithm of the TPPs concentration (μg / mL) was created. Figure 4 As shown, the linear regression equation is Y = 0.12 × logC + 0.2 (R² - 0.12 × logC + 0. ... 2 =0.9985)( Figure 4 (b) The linear range is 0.0001~500 μg / mL ( Figure 4 (a) The detection limit (3σ / S) was calculated to be 0.047 ng / mL.

[0057] The experimental results of this embodiment show that the OAm / TFPro PQDs probe has a wide linear range and a low detection limit for TPPs detection.

[0058] Example 3: Selectivity Study of ECL Sensor

[0059] To verify the specificity of the ECL sensing platform based on OAm / TFPro PQDs probes for TPPs, under the same test conditions as in Example 2, various potential interfering substances that may exist in actual samples were used to replace the TPPs in the tests. The details are as follows:

[0060] 6.0 μL of diluted OAM / TFPro PQDs was drop-coated onto a polished GCE surface and dried at room temperature to prepare the working electrode. This electrode, along with the reference and counter electrodes, was then inserted into a 0.1 M PBS buffer (pH 7.4) containing 0.1 M K2S2O8 and various potential interfering substances to form a three-electrode system. The potential scan range was set to 0 V to -2.2 V, the scan rate to 100 mV / s, and the photomultiplier tube voltage to 600 V, and the ECL signal was recorded. The signal trend was then plotted based on the ECL quenching degree of the OAM / TFPro PQDs probe ([(ECL0-ECL) / ECL0]) to evaluate the sensor's selectivity.

[0061] Interfering substances and their concentrations are as follows: histidine (500 µM), theophylline (350 µM), theanine (500 µM), cysteine ​​(500 µM), glucose (500 µM), lactose (500 µM), fructose (500 µM), sucrose (500 µM), and Hg. 2+ (500 µM), Ag + (500 µM), Fe 2+ (500 µM), Al 3+ (500 µM), Ca 2+ (500 µM), K + (500 µM), Mg2+ (500 µM), Cu 2+ (500 µM), Zn 2+ (500 µM), NO3 - (500 µM), Cl - (500 µM), SO4 2- (500 µM). TPPs (100 µg / mL, approximately 350 µM) were also tested as a control.

[0062] The results are as follows Figure 5 As shown, the quenching efficiency of ECL signals caused by all interfering factors is less than 30%, while the quenching efficiency caused by TPPs is as high as 80%.

[0063] The experimental results of this embodiment show that the ECL sensing platform constructed based on OAm / TFPro PQDs probes can specifically detect polyphenol molecules in food. Under the condition of pH 7.4, the sensing platform exhibits high selectivity for polyphenol molecules in food.

[0064] Example 4: Stability Test of OAm / TFPro PQDs Probes

[0065] To verify the aqueous ECL stability of the OAm / TFPro PQDs probe, the ECL performance of the OAm / TFPro PQDs probe stored for different periods was tested under the same test conditions as in Example 2. Details are as follows:

[0066] First, the OAM / TFPro PQDs precursor solution, stored for a certain period of time, was diluted 10-fold. Then, 6.0 μL of the diluted OAM / TFPro PQDs was drop-coated onto a clean, polished GCE surface and dried at room temperature to prepare the working electrode. Next, it, along with the reference electrode (Ag / AgCl) and the counter electrode (Pt wire), was inserted into a PBS buffer (0.1 M, pH 7.4) containing 0.1 M K₂S₂O₈ and various potential interfering substances to form a three-electrode system. The potential scan range was set to 0 V to -2.2 V, the scan rate to 100 mV / s, and the photomultiplier tube voltage to 600 V. The ECL signal was recorded. Then, a signal trend graph was plotted based on the ECL luminescence intensity of the OAM / TFPro PQDs probe to evaluate the probe's aqueous stability.

[0067] like Figure 6 As shown, the electrode modified with OAm / TFPro PQDs maintained good ECL performance for 45 days, indicating that the probe material can maintain good photophysical performance for a long time in the aqueous phase.

[0068] Example 5: Detection of TPPs in Tea Based on OAm / TFPro PQDs Probes

[0069] To verify the ability of the ECL sensing platform based on OAm / TFPro PQDs probes to analyze and detect TPPs in real samples, the platform was evaluated by detecting the TPP content in actual tea leaves (green tea and white tea) under the same test conditions as in Example 2 using the standard spiked recovery method. Details are as follows:

[0070] First, purchase two different types of tea, green tea and white tea, from a local supermarket. Take 2g of each type of tea leaves and steep them in 200mL of boiling water for 10 minutes, then cool to room temperature. Collect the supernatant by filtration and centrifugation. Then dilute with purified water 20 times to obtain a clear tea liquid, which is stored in a brown bottle at 4℃ for later use.

[0071] 6.0 μL of diluted OAm / TFPro PQDs was drop-coated onto a polished GCE surface and dried at room temperature to prepare the working electrode. Then, it, along with the reference electrode (Ag / AgCl) and the counter electrode (Pt wire), was inserted into a PBS buffer (0.1 M, pH 7.4) containing 0.1 M K₂S₂O₈, the prepared tea stock solution (tea to PBS buffer volume ratio 1:4), and different concentrations of TPPs standards (30, 50, 70 µg / mL) to form a three-electrode system. The potential scan range was set to 0 V to -2.2 V, the scan rate to 100 mV / s, and the photomultiplier tube voltage to 600 V to record the ECL signal. Then, the concentration of TPPs in the test solution was calculated based on the standard curve between the probe's ECL quenching degree ([(ECL0-ECL) / ECL0]) and TPPs. Each tea sample was tested in triplicate. The results are expressed as mean ± standard deviation. The recovery rate and relative standard deviation (RSD) were calculated. The experimental results are shown in Table 1 below.

[0072] Table 1. Analytical results of TPPs in actual tea samples (±SD, n=3)

[0073]

[0074] As shown in Table 1, the ECL sensing platform constructed based on OAm / TFPro PQDs probes can perform well in detecting TPPs in actual samples, with a recovery rate in the range of 98.0% to 105.3% and an RSD of less than 3%, indicating that the ECL sensing platform has good accuracy in the analysis of polyphenol molecules in food.

[0075] The embodiments described above are only some, not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. The scope of protection of the present invention is determined by the scope claimed in the claims. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing an aqueous-phase stable electrochemiluminescent perovskite quantum dot probe, characterized in that, Includes the following steps: Step 1) PbBr2, CsBr and 2-methylimidazole are dissolved in N,N-dimethylacetamide and stirred at 60°C; then oleylamine and trifluoropropionic acid are added to the reaction system simultaneously and the reaction is continued at 60°C. Step 2) The reaction solution obtained in step 1) is injected into ethyl acetate, allowed to stand at 60°C to crystallize, the precipitate is collected by centrifugation, and then ultrasonically dispersed in the aqueous phase to obtain an aqueous phase-stable OAm / TFPro dual-ligand protected PQDs probe.

2. The method for preparing an aqueous-phase stable electrochemiluminescent perovskite quantum dot probe according to claim 1, characterized in that, Step 1) The amount of PbBr2 used is 146.8 mg; the amount of CsBr is 85.1 mg; the amount of 2-methylimidazole is 8.2 mg; the amount of N,N-dimethylacetamide is 10 mL; the amount of oleylamine is 500 μL; and the amount of trifluoropropionic acid is 300 μL.

3. A PQDs probe prepared by the method according to claim 1 or 2, characterized in that, The PQDs contain a composite crystal form of CsPbBr3 and CsPb2Br5, and their surfaces are jointly modified by OAm and TFPro. They can be stably dispersed in the aqueous phase for a long time and maintain high ECL luminescence efficiency.

4. The PQDs probe according to claim 3, characterized in that, The TFPro prevents water molecules from penetrating into the PQDs core by forming hydrogen bond interfaces between fluorine atoms and water molecules, thereby allowing the PQDs to maintain their structural and luminescent stability in the aqueous phase.

5. The use of the PQDs probe as described in claim 3 or 4 in the preparation of sensors or detection kits for detecting tea polyphenols.

6. An ECL sensing platform for detecting tea polyphenols, characterized in that, include: First, the PQDs probe dispersion as described in claim 3 or 4 is coated on the surface of the working electrode to prepare a modified electrode; then, the modified electrode, the reference electrode, and the counter electrode form a three-electrode system, which is placed in a PBS buffer containing K2S2O8 and the analyte for ECL signal acquisition.

7. The ECL sensing platform according to claim 6, characterized in that, The potential scanning range of the ECL signal acquisition is 0V to -2.2V, the scanning rate is 100 mV / s, and the photomultiplier tube voltage is 600V.

8. A method for detecting tea polyphenols in tea, characterized in that, Using the PQDs probe as described in claim 3 or 4, tea polyphenols are quantitatively detected by the degree of quenching of their electrochemiluminescence signals.

9. The detection method according to claim 8, characterized in that, The linear range for the detection of tea polyphenols is 0.0001 μg / mL to 500 μg / mL.

10. The detection method according to claim 8, characterized in that, The method exhibits high selectivity for tea polyphenols, with common interfering substances including histidine, theophylline, theanine, cysteine, glucose, fructose, sucrose, and Hg. 2+ Ag + Fe 2+ Al 3+ Ca 2 + K + Mg 2+ Cu 2+ Zn 2+ NO3 - Cl - SO4 2- .

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