A donor-acceptor supramolecular fluorescent probe and its application in the detection of pyrethroid pesticide residues

Abstract

The present invention discloses a novel flavonoid fluorescent dye AFL and combines it with albumin ALB to obtain an AFL@ALB supramolecular fluorescent probe. In the AFL@ALB supramolecular fluorescent probe, ALB is an energy donor and AFL is an energy acceptor; after adding pyrethroid pesticides to the probe, the environmental polarity of the flavonoid fluorescent dye is changed due to the binding of pyrethroid pesticides to albumin (pyrethroid pesticides, as hydrophobic compounds, can bind to albumin with high binding affinity), resulting in the fluorescence color of the AFL@ALB supramolecular fluorescent probe changing from yellow to green within 10 seconds. The linear range of the probe for detecting pyrethroid pesticide residues is 0-170μM, the detection limit is as low as 1.0773μM, the selectivity is good, the anti-interference ability is strong, and the color change is obvious.

Description

Technical Field

[0001] The present invention relates to a donor-acceptor supramolecular fluorescent probe based on AFL@ALB and application thereof in detection of pyrethroid pesticide residues, belonging to the fields of material synthesis, visual detection, food quality monitoring, etc. Background Art

[0002] Pyrethrin pesticides are commonly used insecticides in residential environments and have multiple uses. Due to their strong insecticidal efficacy and strong contact effect, pyrethrin pesticides can control a variety of pests. In recent years, judging from the annual use of pyrethrin active ingredients worldwide, the demand for pyrethrin pesticides in various countries has also been increasing. As a major agricultural country, the widespread use of pyrethrin pesticides is necessary in my country. On the one hand, pyrethrin pesticides can greatly improve the yield and quality of agricultural products. On the other hand, the residues caused by the abuse of pyrethrin pesticides will pollute agricultural products, the environment, soil, water, etc., and improper use will cause various diseases and signs of poisoning to people.

[0003] To date, the commonly used large-scale instrumental analysis methods include high performance liquid chromatography, gas / liquid chromatography-mass spectrometry and surface enhanced Raman scattering. These methods can indeed provide accurate and reliable results, but due to the complexity of their sample pretreatment, the huge instruments and equipment cannot achieve real-time and rapid detection. Molecular imprinting technology relies on its own specific affinity and selectivity, and has become the mainstream technology in the field of rapid detection of pyrethroid pesticide residues. However, there are still many problems with molecular imprinting that need more investment to solve, such as cumbersome pretreatment, and the credibility of ultra-trace detection results is greatly reduced. The detection speed and convenience also need to be improved, and on-site detection of pyrethroid pesticides cannot be achieved. Therefore, it is urgent to develop a simple, convenient, sensitive and reliable method for rapid quantitative detection of pyrethroid pesticide residues. Summary of the invention

[0004] The purpose of the present invention is to provide a donor-acceptor supramolecular fluorescent probe AFL@ALB, and use it for high-sensitivity visual quantitative detection of pyrethroid pesticide residues. The sensing detection system can realize reliable, convenient and on-site pyrethroid pesticide residue detection.

[0005] In the field of fluorescence imaging, organic dyes with donor-acceptor (DA) electronic structures are the most commonly used fluorescent dyes for developing imaging fluorescent agents. Donor-acceptor materials will show different fluorescence in different polar solvent environments. Based on this, we designed and synthesized composite materials of DA-type dyes combined with albumin. Pesticides, as a hydrophobic compound, can bind to albumin with strong affinity; and albumin can bind to many ligands, including small molecule fluorescent dyes. When the donor-acceptor (DA) fluorescent dye with solvated fluorescence color change characteristics is first bound to albumin, after adding pyrethroid pesticides, the coexistence of pyrethroid pesticide molecules and proteins will change the environmental polarity of the DA dye, thereby causing the fluorescence color of the dye to change, realizing the visual fluorescence detection of pyrethroid pesticides. Compared with molecular imprinting, this method will be simpler and more efficient. We successfully synthesized and characterized the new fluorescent dye AFL. Albumin (ALB) has multiple topological binding cavities and can bind to a variety of ligands such as the small molecule fluorescent dye AFL. ALB can be used as a host to construct a host-guest supramolecular system with AFL, thereby forming an AFL@ALB complex in which ALB and AFL are physically bound. When pyrethroid pesticides are added to the supramolecular fluorescent system AFL@ALB, there is a competitive relationship between pyrethroid pesticides and AFL for binding to albumin. As a hydrophobic compound, pyrethroid pesticides can bind to albumin with high binding affinity, so that the addition of pyrethroid pesticides to the AFL@ALB supramolecular fluorescent system changes the environmental polarity of the AFL@ALB system and achieves a color change, so that the AFL@ALB complex can be used as a supramolecular fluorescent probe to achieve visual detection of pyrethroid pesticide residues from yellow to green, with high sensitivity, high specificity and good anti-interference ability.

[0006] In order to achieve the above technical purpose of the present invention, the present invention adopts the following technical solutions:

[0007] First, the present invention provides a novel flavonoid fluorescent dye AFL, the molecular formula of which is 20 H 19 O4N, the structural formula is as follows:

[0008]

[0009] In the present invention, the chemical structure of AFL contains a group of electron donors (dimethylamine) and acceptors (chromanone), as follows:

[0010]

[0011] The donor acceptor undergoes intramolecular charge transfer (ICT) when excited. In the field of fluorescence imaging, organic dyes with DA (donor-acceptor) electronic structure are the most commonly used fluorescent dyes for developing two-photon imaging fluorescent reagents. Intramolecular charge transfer occurring in the donor-acceptor fluorophore skeleton can lead to solvation fluorescence chromism. Donor-acceptor fluorescent materials will show different fluorescence in different polar solvent environments. Pyrethroids can change the environment of DA composite materials so that the fluorescence wavelength of the composite materials changes, achieving a color change effect, thereby realizing the visual detection of pyrethroid pesticides.

[0012] Secondly, the present invention also provides a preparation method of the novel flavonoid fluorescent dye AFL, which comprises the following steps: dissolving 2-hydroxy-5-methylacetophenone, 4-dimethylaminocinnamaldehyde and tetrahydropyridine in a mixed solution of anhydrous ethanol and tetrahydrofuran, and reacting and stirring at room temperature overnight under a nitrogen or argon atmosphere; rotary evaporating the solution after the reaction to obtain an orange-red solid, dissolving the orange-red solid in anhydrous ethanol, adding 4-6 mol / L KOH solution dropwise until the orange-red solid is completely dissolved, slowly adding 20-40 wt % hydrogen peroxide solution under ice bath conditions, stirring and reacting at room temperature for 15-36 hours, adjusting the pH of the solution to neutral and extracting with dichloromethane, collecting the lower layer of liquid and rotary evaporating and concentrating to obtain a crude product, and purifying it by silica gel column chromatography to obtain a reddish brown solid.

[0013] In the above-mentioned preparation method, the molar ratio of 2-hydroxy-5-methylacetophenone to 4-dimethylaminocinnamaldehyde is preferably 1:1. At the same time, 30-35wt% hydrogen peroxide is added to the reaction, and the reaction is stirred at room temperature for 20-25 hours. The developing solvent (eluent) for silica gel column purification is: dichloromethane: methanol = 20:1 (v / v). The volume ratio of anhydrous ethanol and tetrahydrofuran is 2-6:1, and stirring is generally 8 to 12 hours overnight.

[0014] Thirdly, based on the above-mentioned synthesized flavonoid fluorescent dye AFL, the present invention also provides a donor-acceptor supramolecular fluorescent probe AFL@ALB, which is mainly composed of a flavonoid fluorescent dye AFL and albumin ALB. Since albumin has multiple topological binding cavities, it can bind to a variety of ligands such as amino acids, lipids, drugs and small molecule fluorescent dyes. AFL, as a small molecule fluorescent dye, enters the interior of ALB, forming a composite structure in which AFL is wrapped with a layer of albumin ALB.

[0015] Fourthly, the present invention also provides a method for preparing the donor-acceptor supramolecular fluorescent probe AFL@ALB system, which comprises dissolving albumin ALB in PBS buffer to prepare an albumin ALB solution, dissolving dye AFL in DMSO to prepare an AFL solution; mixing the AFL solution and the albumin ALB solution in PBS buffer for reaction; the ALB solution and the AFL solution have the same concentration, and the volume ratio of the AFL solution to the ALB solution is preferably 1:4. In the formed fluorescent probe AFL@ALB system, the fluorescence intensity of AFL@ALB is the maximum when the concentration ratio of AFL to ALB is 1:4.

[0016] In the above-mentioned preparation method of the fluorescent probe AFL@ALB, the AFL solution and the ALB solution need to be stirred vigorously when mixed to allow them to react fully. At the same time, the PBS buffer used has a pH of 7.0-7.5 and a concentration of 1 mM.

[0017] Fifthly, the present invention also provides the use of the fluorescent probe AFL@ALB in visual detection of pyrethroid pesticide residues. The pyrethroid pesticides include but are not limited to commonly used cypermethrin, cypermethrin, cyhalothrin, deltamethrin, and the like.

[0018] As a preferred solution, the application method can be: using the supramolecular fluorescent probe as a detection reagent, 10 μL of AFL preparation solution and 40 μL of ALB preparation solution are mixed into 1 mL of PBS buffer to prepare an AFL@ALB solution. Then drop it into a 3 mL quartz cuvette, add 2 to 3 μL of pyrethroid pesticide solutions of different concentrations in sequence, and mix and shake for 10 seconds. Use 430 nm as the excitation wavelength to record the fluorescence spectrum of the probe solution in the range of 500 to 740 nm, and establish the relationship between the change in the fluorescence peak wavelength and the concentration of the pyrethroid pesticide to achieve quantitative detection of the pyrethroid pesticide.

[0019] As another preferred embodiment, the application method can also be to first make the fluorescent probe AFL@ALB into a paper-based sensor, add pyrethroid pesticides, and observe the fluorescence color change under ultraviolet light, so as to realize the visual detection of pyrethroid pesticides. Wherein, the preparation of the fluorescent paper-based sensor is to soak the non-fluorescent printing paper in the solution of the AFL@ALB system and then dry it in an oven; when detecting pyrethroid pesticides, the soaked test paper is placed in a culture dish, and different concentrations of pyrethroid pesticides (0-200μM) are added to the test paper in the culture dish respectively, and after the different concentrations of pyrethroid pesticides are completely immersed in the test paper, a UV flashlight (365nm) is used to irradiate and take pictures. Furthermore, the image RGB value can be obtained by the color recognition software (Color recognizer, Xiyi Technology) of a smart phone. Quantitative detection is achieved by using the ratio of R to G and the relationship with the concentration of pyrethroid pesticides. In order to make the test results more accurate, three image acquisition points are selected for testing and calculation to detect the linear relationship between the ratio of R / G of the test paper and the pyrethroid pesticides.

[0020] The present invention synthesizes a novel flavonoid fluorescent dye (AFL), which emits different fluorescence in different solvents due to different solvent polarities, and emits weak red fluorescence in water; on this basis, after adding albumin (ALB), it will emit bright orange-yellow fluorescence, thereby forming an AFL@ALB supramolecular fluorescent probe. In the AFL@ALB supramolecular fluorescent probe, ALB is an energy donor and AFL is an energy acceptor; after adding pyrethroid pesticides to the probe, the environmental polarity of the flavonoid fluorescent dye is changed due to the binding of pyrethroid pesticides to albumin (AFL is wrapped with a layer of albumin, so the pyrethroid pesticides only contact with albumin and are difficult to directly bind to the dye AFL), resulting in the fluorescence color of the AFL@ALB supramolecular fluorescent probe changing from yellow to green within 10 seconds. The linear range of the probe for detecting pyrethroid pesticide residues is 0-170μM, the detection limit is as low as 1.0773μM, good selectivity, strong anti-interference ability, and obvious color change. In addition, this method can be successfully applied to the detection of pyrethroid pesticide residues in real samples, providing a new idea for the visual fluorescence quantitative detection of pyrethroid pesticides.

[0021] The present invention synthesizes a novel DA-type fluorescent dye as a main body, proposes a fast, sensitive and simple supramolecular fluorescent probe, and performs composite quantitative detection of pyrethroid pesticides with the guest albumin, thereby realizing visual detection of pyrethroid pesticides. The fluorescent probe can detect pyrethroid pesticides sensitively, and can realize that with the addition of pyrethroid pesticides, the fluorescence color of the supramolecular fluorescent probe changes from yellow to green. This is because the addition of pyrethroid pesticides changes the environmental polarity of the supramolecular fluorescent probe, and the flavonoid fluorescent dye has the characteristic that the fluorescence wavelength changes with the change of environmental polarity, thereby causing the fluorescence color of the supramolecular fluorescent probe to change after the addition of pyrethroid pesticides, thereby realizing the purpose of visual detection of pyrethroid pesticides. The continuous change of fluorescence wavelength realizes the visual detection of pyrethroid pesticides, and the detection limit in PBS buffer solution (pH7.4) within 10s is 1.0773μM. Therefore, the supramolecular fluorescent probe provides a new method for quantitative detection of pyrethroid pesticides, and can be extended to the detection of other analytes or trace hazards in the field of analytical science.

[0022] Compared with the existing detection technology, the beneficial effects of the present invention are embodied in:

[0023] 1. The supramolecular fluorescent probe of the present invention detects pyrethroid pesticides, and shows better visual detection effect compared with other monochromatic fluorescence detection (visually, the supramolecular fluorescent probe solution added with pyrethroid pesticides shows a color change from yellow to green under ultraviolet light, which is more obvious than the color change of quenching or opening of a single fluorescent color), effectively avoiding the instability problem of monochromatic fluorescence intensity and realizing visual detection.

[0024] 2. The detection limit of pyrethroid pesticides on the fluorescence spectrometer of the present invention is 1.0773 μM, which is lower than the permissible limit of pyrethroid pesticide residues.

[0025] 3. The fluorescent sensing system of the supramolecular fluorescent probe based on AFL fluorescent dye and ALB prepared by the present invention has good selectivity and sensitivity to pyrethroid pesticides, can effectively avoid interference from other impurities, and has a fast response.

[0026] 4. The response time of the supramolecular fluorescence sensor of the present invention is completed within ten seconds, thus realizing the rapid detection of pyrethroid pesticides.

[0027] 5. The fluorescent paper-based sensor of the present invention is safe, stable and easy to carry, breaking the limitations of time and space.

[0028] 6. By introducing smartphones to detect RGB, the use of large instruments can be avoided to a certain extent. Only a portable UV lamp is needed to realize the real-time / on-site visual quantitative detection of pyrethroid pesticides by fluorescent nanosensors, making the detection process portable, fast and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the mass spectrum of AFL.

[0030] Figure 2 It is AFL NMR 1 H spectrum and 13 C spectrum.

[0031] Figure 3 This is the UV diagram of the solvation characteristics of AFL.

[0032] Figure 4 This is the fluorescence image of the AFL solvation characteristics.

[0033] Figure 5 It is the fluorescence diagram of the supramolecular fluorescence system and the wavelength shift diagram after adding pyrethroid pesticide.

[0034] Figure 6 Figure 1 is a graph showing the stabilization time of the fluorescence sensing system. (A) The kinetic response of adding ALB to AFL. (B) The reaction is stable within 1 min.

[0035] Figure 7 The optimal reaction time of the fluorescence sensing system. (A) Kinetic response of AFL@ALB to pyrethroid pesticides. (B) The reaction is stable within 10 s.

[0036] Figure 8 It is the optimal concentration ratio of AFL to ALB in the fluorescence sensing system.

[0037] Fig. 9 (A) is the normalized curve and color change diagram of the fluorescence spectrum of the supramolecular fluorescent probe for different concentrations of pyrethroid pesticides. (B) is the fluorescence spectrum between the fluorescence wavelength and the concentration of pyrethroid pesticides. (C) is the relationship between the fluorescence wavelength and the concentration of pyrethroid pesticides. There is a linear relationship between the fluorescence wavelength and the concentration of pyrethroid.

[0038] Fig.10 (A) is the albumin system under different concentrations of pyrethroids. (B) is the relationship between albumin fluorescence intensity and pyrethroid concentration. There is a linear relationship between albumin fluorescence intensity and pyrethroid concentration. Pyrethroid pesticides can reduce the fluorescence intensity of albumin, indicating that pyrethroid pesticides can bind to albumin.

[0039] Fig.11 The following is a comparison of the H NMR spectra of AFL before and after the addition of pyrethrin. The spectrum of AFL in the presence of pyrethrin does not show any new peaks or peak shifts compared to the two individual compounds. This result indicates that pyrethrin is chemically inert to AFL, and therefore the fluorescence response is not caused by changes in the chemical structure of the fluorophore.

[0040] Fig.12(A) is a graph showing the color change of the fluorescent paper-based sensor after adding different concentrations of pyrethroid pesticides. (B) is a graph showing the linear relationship between the red channel / green channel ratio of the fluorescent paper-based sensor and the pyrethroid concentration. (C) is a graph showing the color change of the supramolecular fluorescent probe solution with different concentrations of pyrethroid. (D) is a graph showing the linear relationship between the red channel / green channel ratio of the supramolecular fluorescent probe solution and the pyrethroid concentration.

[0041] Fig.13 (A) is the selectivity graph of supramolecular fluorescent probe. (B) is the anti-interference graph of supramolecular fluorescent probe. DETAILED DESCRIPTION

[0042] The following embodiments are further descriptions of the content of the present invention as an explanation of the technical content of the present invention, but the essential content of the present invention is not limited to the following embodiments. Ordinary technicians in this field can and should know that any simple changes or replacements based on the essential spirit of the present invention should fall within the scope of protection required by the present invention.

[0043] Embodiment 1:

[0044] Preparation of AFL flavonoid dye

[0045] 2-Hydroxy-5-methylacetophenone (3.0 g, 0.02 mol), 4-dimethylaminocinnamaldehyde (3.5 g, 0.02 mol) and 45 μL tetrahydropyridine were dissolved in a mixed solution of 80 mL anhydrous ethanol and 20 mL tetrahydrofuran, and stirred overnight at room temperature under a nitrogen atmosphere. The solution after the reaction was rotary evaporated to obtain an orange-red solid, which was dissolved in 100 mL anhydrous ethanol, and 10 mL KOH aqueous solution (2.8 g, 0.05 mol) was added dropwise until the orange-red solid was completely dissolved. Then, 5 mL 30 wt% hydrogen peroxide solution was slowly added in an ice bath, and after stirring at room temperature for 24 h, the solution was adjusted to neutral with 1 mol / L dilute hydrochloric acid and extracted with dichloromethane. The lower layer of liquid was collected and concentrated by rotary evaporation, and the crude product was subjected to silica gel column chromatography (developing solvent: dichloromethane: methanol = 20:1) to obtain a reddish brown solid with a yield of 28.7%).

[0046] Embodiment 2:

[0047] Preparation of supramolecular fluorescent probes

[0048] 66.5 mg of albumin (CAS: 70024-90-7, Aladdin, relative molecular mass 66.5 kD) was dissolved in 1 mL of PBS buffer solution (1 mM, pH = 7.4) to prepare a 1 mM albumin solution, and 3.6 mg of AFL was dissolved in 10 mL of DMSO to prepare a 1 mM AFL solution. 10 μL of AFL preparation solution and 40 μL of ALB preparation solution were mixed in 1 mL of PBS buffer to obtain an AFL@ALB solution (10 μM). In order for AFL and ALB to react fully, the mixed solution of AFL and ALB can be vigorously stirred for 50 seconds and kept stable for 10 seconds before being used in the next step. Time-dependent experiments show that the fluorescence intensity of AFL@ALB remains stable within 1 minute.

[0049] Embodiment 3:

[0050] Supramolecular fluorescent probes, component characterization and optimization of detection conditions

[0051] 1. The supramolecular fluorescent probe emits obvious orange-yellow fluorescence under 430nm ultraviolet excitation. After the introduction of pyrethroid pesticides, the orange-yellow fluorescence of AFL at 590nm can be changed to green fluorescence within 10s through the solvation characteristics, which can realize the rapid visual detection of pyrethroid pesticides by the supramolecular fluorescent probe system, and the content of pyrethroid pesticides in the sample can be detected by the degree of change of fluorescence wavelength in the supramolecular fluorescent system.

[0052] 2. Characterization of components of supramolecular fluorescent probe sensing system

[0053] Considering that the detection sensitivity of the probe to the analyte is related to its own properties, mass spectrometry, nuclear magnetic resonance and fluorescence spectroscopy were used to study the structural characteristics and spectral properties of the supramolecular fluorescent nanoprobe.

[0054] 3. Effects of reaction time, pH and AFL@ALB fluorescence intensity ratio on supramolecular fluorescent probe

[0055] Reaction time, pH and AFL / ALB fluorescence intensity ratio have certain effects on the fluorescence intensity and detection effect of the supramolecular fluorescent probe.

[0056] Reaction time Figure 6 As shown in the figure, the kinetic test results show that the fluorescence tends to stabilize within 10 seconds after the addition of pyrethroid pesticides. Albumin remains stable at pH = 7.4. Considering comprehensively, we choose 10 seconds as the best reaction time and 7.4 as the best pH value for detection.

[0057] The reaction starting concentration ratio of AFL and ALB in the probe solution plays an important role in the detection effect of pyrethroid pesticides. Figure 8As shown, under 365 nm ultraviolet light, when the reaction starting concentration ratio of AFL and ALB was adjusted to 1:4, the fluorescence intensity of AFL@ALB was the strongest.

[0058] Embodiment 4:

[0059] 1. Detection of pyrethroid pesticides by supramolecular fluorescent probe solution

[0060] The supramolecular fluorescent probe solution prepared in Example 1 was dripped into a 3 mL quartz colorimetric tube, and 2 to 3 μL of pyrethroid solutions of different concentrations were added in sequence, and the mixture was mixed and shaken evenly. Obvious fluorescence color changes can be observed under ultraviolet light, and visual detection of pyrethroid pesticides can be achieved. The fluorescence spectrum of the solution in the range of 500 to 700 nm was recorded with 430 nm excitation light, and the relationship between the change in the fluorescence peak wavelength ratio and the concentration of pyrethroid pesticides was established to achieve quantitative detection of pyrethroid pesticides.

[0061] 2. Drawing of standard curve

[0062] Different concentrations of pyrethroid pesticide solutions were added to the mixed system of AFL@ALB supramolecular fluorescent probe. After mixing, the fluorescence wavelength was tested. The results showed that the orange-yellow fluorescence wavelength emission peak at 590nm gradually shifted to the left. By establishing the relationship between the fluorescence wavelength and the concentration of pyrethroid pesticides, quantitative detection of pyrethroid pesticides can be achieved. When the excitation light is 430nm, the fluorescence spectrum of the mixed system in the wavelength range of 500-700nm is recorded. Fig. 9 The relationship between the fluorescence wavelength and the concentration of the pyrethroid pesticide is shown. The change in the fluorescence wavelength is linearly related to the concentration of the pyrethroid pesticide, where the horizontal axis is the concentration of the pyrethroid pesticide and the vertical axis is the fluorescence wavelength.

[0063] Embodiment 5:

[0064] Detection of pyrethroid pesticides using fluorescent paper-based sensors

[0065] 1. Preparation of fluorescent paper-based sensor: The test paper is purchased non-fluorescent printing paper. First, cut the test paper into several 1*4cm strips, soak them in AFL@ALB solution overnight, and dry them in an oven for 4 hours for later use.

[0066] 2. Drawing of standard curve:

[0067] When testing pyrethroid pesticides, we put the test paper in a petri dish, drip different concentrations of pyrethroid pesticides (0-200μM) into the test paper in the petri dish, and put it into the detection platform after the different concentrations of pyrethroid pesticides completely immerse the test paper. In a dark environment, a 365nm ultraviolet lamp is used as the light source to obtain the fluorescence image through a smartphone. It is further decomposed into RGB values, and quantitative detection is completed by installing a color recognition application (APP). Fig.12It shows that R / G is linearly related to the concentration of pyrethroid pesticides, where the horizontal axis is the concentration of pyrethroid pesticides and the vertical axis is the RGB ratio.

[0068] Embodiment 6:

[0069] Selectivity and interference test of supramolecular fluorescent probe

[0070] Chlorantraniliprole, carbaryl, cyantraniliprole, tetrachlorvinphos, glyphosate, tetrazopyra, glufosinate, beta-cypermethrin, cypermethrin, cyhalothrin, and deltamethrin were added to the supramolecular fluorescent probe system at a concentration of 100 μM for selectivity testing. Fig.13 (A). The test results show that the probe only responds to pyrethroid pesticides. 100 μM of common interfering substances (1.K + ,2.Ca 2+ ,3.Na + ,4.Mg 2+ ,5.NH4 + ,6.Cl - ,7.SO4 2- ,8.SO3 2- ,9.HCO3 - ,10.H2PH4 - ,11.glucose,12.fructose,13.lysine,14.tryptophan,15.SDBS,16.tween 80,17.PEG4000,18.span 80), there is no obvious change in the fluorescence wavelength, such as Fig.13 (B) shows that common interfering substances can coexist with pyrethroid pesticides. The results show that the system has good selectivity for pyrethroid pesticides and anti-interference to other common substances. Fig.13 In (B), the left column is without adding pyrethroid pesticides, and interfering substances are directly added to measure whether the interfering substances have a direct impact on the supramolecular probe solution, that is, the selectivity of the probe solution to the interfering substances. The right column is adding pyrethroid pesticides and then adding interfering substances to observe the anti-interference properties of the supramolecular probe solution to pyrethroid pesticides.

[0071] It should be noted that the above-mentioned technical contents of the present invention are only for explanation and clarification to enable those skilled in the art to understand the technical essence of the present invention, so the technical contents are not used to limit the substantial protection scope of the present invention. The substantial protection scope of the present invention shall be subject to the claims. Those skilled in the art should know that any modification, equivalent substitution and improvement based on the substantial spirit of the present invention shall be within the substantial protection scope of the present invention.

Claims

1. A new type of flavonoid fluorescent dye AFL, molecular formula C 20 H 19 O4N, the structural formula is as follows: 。 2. The method for preparing the novel flavonoid fluorescent dye AFL according to claim 1, characterized in that: The steps include: 2-Hydroxy-5-methylacetophenone, 4-dimethylaminocinnamaldehyde and tetrahydropyridine are dissolved in a mixed solution of anhydrous ethanol and tetrahydrofuran, and reacted and stirred at room temperature overnight under a nitrogen or argon atmosphere; the solution after the reaction is rotary evaporated to obtain an orange-red solid, the orange-red solid is dissolved in anhydrous ethanol, a 4-6 mol / L KOH aqueous solution is added dropwise until the orange-red solid is completely dissolved, and a 20-40wt% hydrogen peroxide solution is slowly added under an ice bath condition, and the reaction is stirred at room temperature for 15-36h, the pH of the solution is adjusted to neutral, and extracted with dichloromethane, the lower layer of liquid is collected and concentrated by rotary evaporation to obtain a crude product, and the product is purified by silica gel column chromatography to obtain a reddish brown solid.

3. The preparation method according to claim 2, characterized in that: The molar ratio of 2-hydroxy-5-methylacetophenone to 4-dimethylaminocinnamaldehyde is 1:

1.

4. The preparation method according to claim 2, characterized in that: Add 30-35 wt% hydrogen peroxide and stir the reaction at room temperature for 20-25 h.

5. A donor-acceptor supramolecular fluorescent probe AFL@ALB, which is a composite of the dye AFL described in claim 1 and albumin ALB.

6. A method for preparing a donor-acceptor supramolecular fluorescent probe AFL@ALB, comprising dissolving albumin ALB in a PBS buffer to prepare an albumin ALB solution, dissolving the dye AFL described in claim 1 in DMSO to prepare an AFL solution; mixing the AFL solution and the albumin ALB solution in a PBS buffer for reaction; the ALB solution and the AFL solution have the same concentration, and the volume ratio of the AFL solution to the ALB solution is 1:

4.

7. The preparation method according to claim 6, characterized in that: The AFL solution and the ALB solution were stirred vigorously when mixed to allow them to react fully.

8. The preparation method according to claim 6, characterized in that: PBS buffer pH=7.0-7.

5.

9. Use of the fluorescent probe AFL@ALB according to claim 5 in visual detection of pyrethroid pesticide residues, wherein the pyrethroid pesticide is selected from cypermethrin, cypermethrin, cyhalothrin and deltamethrin.

10. The use according to claim 9, characterized in that Pyrethroid pesticides can be added to the fluorescent probe AFL@ALB system or the fluorescent probe AFL@ALB can be made into a paper-based sensor and then pyrethroid pesticides can be added. Then, the fluorescence color change can be observed under ultraviolet light to achieve visual detection of pyrethroid pesticides.

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