Fluorescent switch sensor based on quantum dot-nano porphyrin and application

Abstract

The invention relates to the technical field of analysis and detection, in particular to a fluorescent switch sensor based on quantum dot-nano porphyrin and application. The specific technical scheme is as follows: the fluorescent switch sensor is constructed by utilizing cadmium telluride quantum dots modified by mercaptosuccinic acid and a 5, 10, 15, 20-tetra (4-nitrophenyl) porphyrin nano material modified by a cationic surfactant hexadecyl trimethyl ammonium bromide. And the method has a good enrichment effect on zearalenone. The sensor has high sensitivity, high selectivity and anti-interference performance, can accurately analyze trace zearalenone in actual grain samples (corn, rice, soybean and the like), and has the advantages of simplicity in operation, low detection limit, high sensitivity, low cost and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of analytical detection technology, in particular to a kind of quantum dot-nanometer porphyrin-based fluorescence switch sensor and application, more particularly to a kind of fluorescence switch sensor constructed by using mercapto succinic acid modified cadmium telluride quantum dots and cationic surfactant hexadecyl trimethyl ammonium bromide modified 5,10,15,20-tetra (4-nitrophenyl) porphyrin nanomaterial. BACKGROUND

[0002] Zearalenone (ZENs) is a secondary metabolite produced by fungi, has immunotoxicity, hepatotoxicity and hematotoxicity, can induce pathological changes of animal or human tissues, affect its endocrine, genetic, liver function, etc., and even can induce cancer. Once contaminated, it spreads very quickly. Therefore, it is urgent to develop a simple, rapid and accurate analysis method to realize the high sensitivity and strong specificity detection of ultra trace ZENs generated by early moldy grain food.

[0003] Traditional methods for detecting mycotoxins generally use chromatographic analysis, enzyme-linked immunosorbent assay, high performance liquid chromatography, etc. Although they have the characteristics of high sensitivity and high accuracy, these techniques are time-consuming, high cost and require high-precision instruments or sample preparation. For example, researchers have screened aptamers with high affinity and specificity to ZENs by using aptamers with high affinity and specificity to antibodies 8Z 31 , constructed a nucleic acid aptamer fluorescence analysis method based on 8Z 31 , the linear range and detection limit were 3.14 nmol / L-31.4 umol / L, 7.85 x 10 -10 mol / L, respectively. This method was used for the detection of ZENs in beer, and the recovery rate was 85.0%-105.1%. However, it is still difficult to meet the ultra trace detection. SUMMARY

[0004] In view of the shortcomings of the prior art, the present application provides a kind of quantum dot-nanometer porphyrin-based fluorescence switch sensor and application, which is constructed by using mercapto succinic acid modified cadmium telluride quantum dots and cationic surfactant hexadecyl trimethyl ammonium bromide modified 5,10,15,20-tetra (4-nitrophenyl) porphyrin nanomaterial, the raw material is easy to obtain, low cost, and can be used for qualitative and quantitative analysis of zearalenone and detection of complex matrix rich in such compounds.

[0005] To achieve the above purpose, the technical scheme is as follows:

[0006] The application discloses a preparation method of a quantum dot-nanometer porphyrin-based fluorescence switch sensor.

[0007] (1) Synthesis of CdTe QDs

[0008] Dissolve cadmium chloride and mercaptosuccinic acid in ultrapure water, after stirring, adjust the pH to alkaline, after stirring at room temperature under nitrogen atmosphere, inject sodium tellurite aqueous solution, then add sodium borohydride aqueous solution, continue to stir under nitrogen atmosphere, and then hydrothermal reaction at 200℃ for 30min, to obtain CdTe QDs;

[0009] (2) Synthesis of nano-porphyrin

[0010] Heat the water bath to 40℃, dissolve 5,10,15,20-tetra(4-nitrophenyl) porphyrin in DMF, and then drop into the aqueous solution of cetyltrimethylammonium bromide drop by drop, and slowly stir, to obtain nano-porphyrin solution;

[0011] (3) Synthesis of quantum dot-nano-porphyrin fluorescent switch sensor

[0012] Add nano-porphyrin solution to CdTe QDs to obtain fluorescent switch sensor.

[0013] Preferably, in step (1), the molar ratio of cadmium chloride and mercaptosuccinic acid is 0.5-1.5:0.8-2.0, the mass-volume ratio of cadmium chloride to ultrapure water is 1:200-300, and the mass-volume ratio of mercaptosuccinic acid to ultrapure water is 1:200-330.

[0014] Preferably, in step (1), the mass-volume ratio of sodium tellurite to water is 1:20-30, and the mass-volume ratio of sodium borohydride to water is 1:12-25.

[0015] Preferably, in step (2), the concentration of 5,10,15,20-tetra(4-nitrophenyl) porphyrin is 6×10 -4 -9×10 -4 mol / L, and the concentration of cetyltrimethylammonium bromide aqueous solution is 2-7mmol / L.

[0016] Preferably, in step (3), the concentration of nano-porphyrin is 2×10 -9 -1×10 -7 mol / L, and the concentration of CdTe QDs is 8×10 -9 -3×10 -8 mol / L.

[0017] Preferably, in step (3), the volume ratio of CdTe QDs and nano-porphyrin is 1:3-3:1.

[0018] Correspondingly, a quantum dot-nanoporphyrin-based fluorescent switch sensor is prepared by the preparation method.

[0019] Correspondingly, the application of the quantum dot-nanoporphyrin-based fluorescent switch sensor in detecting zearalenone.

[0020] Preferably, the minimum detection limit of the fluorescent switch sensor for zearalenone is 6*10 -15 mol / L.

[0021] Correspondingly, a visual paper-based sensor is constructed by loading the quantum dot-nanoporphyrin-based fluorescent switch sensor on a portable paper-based chip.

[0022] The application has the following beneficial effects:

[0023] The composite fluorescent switch sensor constructed by the mercaptobutane disulfide modified cadmium telluride quantum dots (CdTe QDs) and 5,10,15,20-tetra (4-nitrophenyl) novel spherical nanoporphyrin (NPs) has good enrichment effect, and the detection limit is as low as 6*10 -15 mol / L. Compared with traditional sensors, the sensor has many advantages such as easy-to-obtain raw materials, low cost, high selectivity and the like. In addition, due to the good fluorescent visualization performance of QDs, the sensor can be further prepared as a paper-based sensing chip and can be used for visual and accurate analysis of trace zearalenone in actual grain samples (corn, rice, soybean, etc.). BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 (A) is a TEM image of cadmium telluride quantum dots in Example 1, (B) and (C) are characterization images of the morphology and particle size of the fluorescent switch sensor;

[0025] Figure 2 (A) is a fluorescence intensity diagram of the fluorescent switch sensor (black line) after adding NPs (blue line), the fluorescence intensity diagram of the fluorescent switch sensor after adding ZENs (red line) and the fluorescence intensity diagram of QDs-ZENs (green line); (B) is a fluorescence lifetime diagram of the sensor (QDs-black line, QDs-NPs-red line); (C) is an ultraviolet diagram of the QDs-NPs sensor before adding ZENs (black line) and after adding ZENs (red line);

[0026] Figure 3 It is a diagram of the change of the fluorescence recovery rate I of the sensor with the amount of NPs added;

[0027] Figure 4 It is a diagram of the change of the fluorescence recovery rate I of the sensor with the amount of NPs added; -7(A) QDs-NPs fluorescence recovery graph after adding ZENs; (B) ZENs quantitative curve; (C) relative fluorescence intensity-Log CZENs quantitative linear graph;

[0028] Figure 5 (A) pH stability test graph of the composite probe in the pH range of 5-10; (B) anti-interference test graph of the composite probe after adding common metal ions and amino acids with high concentration (1 x 10 -7

[0029] Figure 6 (A) Selectivity test graph of the fluorescence switch sensor for ZENs;

[0030] Figure 7 (B) Fluorescence contrast column graph of the sensor for actual sample grains (corn, rice, millet, oatmeal, soybean);

[0031] Figure 8 (A) 96-well plate graph of the fluorescence switch sensor for ZENs under UV light;

[0032] Figure 9 (B) Performance test graph of the visualized paper-based sensor. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0034] If not specifically indicated, the technical means used in the examples is the conventional means well known to those of ordinary skill in the art.

[0035] ​The detection mechanism of the composite fluorescent switch sensor constructed by the thiol succinic acid modified cadmium telluride quantum dots and 5,10,15,20-tetra(4-nitrophenyl) nanophthalocyanine lies in that: monodisperse CdTe quantum dots (CdTe QDs) are synthesized by a simple aqueous phase synthesis method, the prepared nanophthalocyanine self-polymer exists in the form of aggregation, when the two are mixed, due to the good enrichment of the nanophthalocyanine, the quantum dots can be enriched on the surface of the nanophthalocyanine and exist in a composite state. After adding 5,10,15,20-tetra(4-nitrophenyl) nanophthalocyanine, the fluorescence of the quantum dots is obviously decreased, and the fluorescence lifetime is also obviously reduced, and the quenching is carried out through the electron transfer of the excited state CdTe quantum dots between the CdTe quantum dots and 5,10,15,20-tetra(4-nitrophenyl) nanophthalocyanine (NPs). After adding ZENs, the fluorescence of the quantum dots is recovered because the combination ability of the nanophthalocyanine and ZENs through hydrogen bond, π-π stacking and the like is stronger than the weak electrostatic interaction between the QDs and NPs, so that the NPs can be pulled away from the surface of the quantum dots. Finally, a kind of strategy with high sensitivity and selectivity is realized, and the ZENs in food is detected by constructing a visual fluorescent "switch" sensor. Meanwhile, the strategy is successfully applied to: it can be attached to paper for visualization.

[0036] The specific scheme is as follows:

[0037] 1. The application provides a fluorescent switch sensor based on quantum dots-nanophthalocyanine, which is composed of thiol succinic acid modified cadmium telluride quantum dots and 5,10,15,20-tetra(4-nitrophenyl) nanophthalocyanine.

[0038] The specific preparation method comprises the following steps:

[0039] (1) Synthesis of cadmium telluride quantum dots (CdTe QDs)

[0040] CdCl2 and thiol succinic acid are dissolved in ultrapure water, stirred for 15 min at normal temperature and pressure, the pH is adjusted to 8-10, and then sodium tellurite aqueous solution and sodium borohydride aqueous solution are injected under a nitrogen atmosphere, and the stirring is continued for 15 min under a nitrogen atmosphere, and then the reaction kettle is quickly placed in a water bath at 200 DEG C for hydrothermal reaction for 30 min, and an orange yellow solution is obtained, that is, CdTe QDs are obtained;

[0041] The CdTe QDs solution is filtered by a microporous filter membrane with a pore size of 0.22 μm, and then the filtrate is transferred to a dialysis bag with a molecular weight cut-off of 3500 Da for dialysis, and the water is changed every 6 h, and the dialysis is continued for about 24 h. The obtained CdTe QDs solution is diluted 100 times with ultrapure water as a stock solution, and is stored in a refrigerator at 4 DEG C.

[0042] The molar ratio of the cadmium chloride and the mercaptosuccinic acid is 0.5-1.5:0.8-2.0, the mass-volume ratio of the cadmium chloride and the ultrapure water is 1:200-300, and the mass-volume ratio of the mercaptosuccinic acid and the ultrapure water is 1:200-330. The mass-volume ratio of the sodium tellurite and water is 1:20-30, and the mass-volume ratio of the sodium borohydride and water is 1:12-25.

[0043] (2) Synthesis of nano-porphyrin (NPs)

[0044] The 5,10,15,20-tetrakis(4-nitrophenyl) porphyrin is dissolved in DMF and added dropwise into the aqueous solution of cetyltrimethylammonium bromide under water bath heating at 40 DEG C, and the nano-porphyrin solution is obtained after slow stirring for 30 min;

[0045] The concentration of the 5,10,15,20-tetrakis(4-nitrophenyl) porphyrin is 6-9*10 -4 -1*10 -7 mol / L, and the concentration of the aqueous solution of cetyltrimethylammonium bromide is 2-7 mmol / L.

[0046] (3) Synthesis of quantum dot-nano-porphyrin fluorescent switch sensor

[0047] The nano-porphyrin solution is added into the CdTe QDs to obtain the fluorescent switch sensor, and the nano-porphyrin quenches the fluorescence of the quantum dots through electron transfer and fluorescence resonance energy transfer. The concentration of the nano-porphyrin is 2*10 -9 -1*10 -7 mol / L, and the concentration of the CdTe QDs is 8*10 -9 -3*10 -8 mol / L. The volume ratio of the CdTe QDs and the nano-porphyrin is 1:3-3:1. When the nano-porphyrin with different concentrations is added into the CdTe QDs, the nano-porphyrin has a good linear relationship with the fluorescence intensity of the CdTe QDs. It should be noted that the concentrations of the nano-porphyrin solution and the CdTe QDs can be appropriately adjusted according to the concentration range of the zearalenone to be detected.

[0048] 2. The application provides a quantum dot-nano-porphyrin fluorescent switch sensor prepared by the preparation method.

[0049] 3. The application provides application of the quantum dot-nano-porphyrin fluorescent switch sensor in detection of zearalenone. The lowest detection limit of the fluorescent switch sensor for zearalenone is 6*10-15 mol / L.

[0050] The application provides a visual paper-based sensor, which is constructed by loading the quantum dot-nanoporphyrin-based fluorescent switch sensor on a portable paper-based chip.

[0051] The technical scheme of the application is further described in detail below with cornotoxin, a mycotoxin small molecule pure substance, and a small molecule compound in a grain substrate as examples, in combination with the drawings.

[0052] The sources of the materials in the following examples are shown in Table 1.

[0053] Table 1 Experimental reagents

[0054] Drug name Purity Production and sales manufacturers [CdCl2.2.5H2O] AR for analysis Aladdin reagent Co., Ltd. 5,10,15,20-tetra (4-nitrophenyl) porphyrin AR for analysis Shanghai source leaf biological technology Co., Ltd. Cetyl trimethyl ammonium bromide AR for analysis Shanghai source leaf biological technology Co., Ltd. Mercapto succinic acid (MSA) AR for analysis Shanghai source leaf biological technology Co., Ltd.

[0055] Example 1

[0056] The preparation process of the fluorescent switch sensor constructed by cadmium telluride quantum dots and nanoporphyrin is as follows:

[0057] (1) Synthesis of CdTe quantum dots

[0058] CdCl2 (0.1650 g, 0.90 mmol) and mercaptosuccinic acid (0.1447 g, 1.2 mmol) were dissolved in 40 mL of ultrapure water, stirred at room temperature and normal pressure for 15 min, the pH was adjusted to 9.70, stirred at room temperature under a nitrogen atmosphere for 20 min, sodium tellurite (0.0399 g, dissolved in 1 mL of ultrapure water) was added using a syringe, and finally sodium borohydride (0.0540 g, dissolved in 1 mL of ultrapure water) was added, and the stirring was continued under a nitrogen atmosphere for 15 min, and then the reaction kettle was quickly placed in a water bath at 200 ℃ for hydrothermal reaction for 30 min, to obtain an orange-yellow solution, namely CdTe QDs. The TEM image is shown in Figure 1 (A).

[0059] The CdTe QDs solution was filtered with a 0.22 μm microporous filter, and then the filtrate was transferred to a 3500 Da dialysis bag for dialysis, and the water was changed every 6 h, and the dialysis was continued for about 24 h. The obtained CdTe QDs solution was diluted 100 times with ultrapure water as a stock solution, and stored in a refrigerator at 4 ℃.

[0060] (2) Synthesis of nanoporphyrin

[0061] A 40 mL aqueous solution of cetyltrimethylammonium bromide with a concentration of 5.0 mmol / L was prepared, and the pH value was adjusted to 8. Then, the water bath was heated to 40 ℃, and 8×10 -4mol / L of 5,10,15,20-tetra(4-nitrophenyl)porphyrin was dissolved in 1 mL of DMF, and then was added dropwise into the above aqueous solution, and was slowly stirred for 30 min, and was stored in a refrigerator at 4 DEG C. TEM image is as shown in Figure 1 (B) shown.

[0062] (3) Synthesis of quantum dot-nanoporphyrin fluorescent switch sensor

[0063] 5,10,15,20-tetra(4-nitrophenyl)nanoporphyrin solution was added into CdTe quantum dots, and NPs quenched the fluorescence of quantum dots through electron transfer and fluorescence resonance energy transfer; when different concentrations of 5,10,15,20-tetra(4-nitrophenyl)nanoporphyrin 2×10 -9 , 4×10 -9 , 6×10 -9 , 8×10 -9 , 4×10 -8 , 6×10 -8 , 8×10 -8 , 1×10 -7 mol / L were added into CdTe quantum dots, the fluorescence intensity of NPs and CdTe quantum dots had a good linear relationship.

[0064] Example 2

[0065] The fluorescent switch sensor constructed in the application is used for identification of zearalenone.

[0066] (I) Detection of zearalenone

[0067] The first group: water (900 μL), cadmium telluride quantum dots (100 μL, 3×10 -10 mol / L); the second group: water (800 μL), cadmium telluride quantum dots (100 μL, 3×10 -10 mol / L) and nanoporphyrin (100 μL), wherein the concentration of nanoporphyrin after adding is 2×10 -9 , 4×10 -9 , 6×10 -9 , 8×10 -9 , 4×10 -8 , 6×10 -8 , 8×10 -8 , 1×10 -7 mol / L, and the fluorescence intensity of NPs and CdTe quantum dots had a good linear relationship.

[0068] Next, the detection of ZENs needs to be specifically described: the first group: water (900 μL), cadmium telluride quantum dots (100 μL, 3×10 -10mol / L); the second group: water (800 μL), cadmium telluride quantum dots (100 μL, 3 x 10 -10 mol / L) and nano- porphyrin (100 μL, 1 x 10 -6 mol / L); the third group: water (730 μL), cadmium telluride quantum dots (100 μL, 3 x 10 -10 mol / L), nano- porphyrin (100 μL, 1 x 10 -6 mol / L) and zearalenone (70 μL, 1 x 10 -6 mol / L); the control group experiment: water (700 μL), cadmium telluride quantum dots (100 μL, 3 x 10 -10 mol / L) and nano- porphyrin (100 μL, 1 x 10 -6 mol / L) and other samples to be detected (100 μL).

[0069] After adding the last reaction material, timing started, and the fluorescence emission spectrum of the system was recorded after 5 min. By extracting the fluorescence peaks between 450 nm and 650 nm in the above fluorescence spectrum, the fluorescence spectrum of the sensor after the addition of ZENs is shown in Figure 2 (A), and the change of the sensor fluorescence recovery rate I with the amount of NPs added is plotted as shown in Figure 3 , F0 is the original fluorescence intensity of the quantum dots, F1 is the quenched fluorescence intensity after the addition of NPs, and F2 is the recovered fluorescence intensity of the quantum dots after the addition of ZENs; wherein the ordinate I = (F2-F1) / F0, and 1 x 10 -7 mol / L is selected as the optimal nano- porphyrin concentration for subsequent experiments.

[0070] The other samples to be detected of the control group experiment were replaced with different concentrations of ZENs (1 x 10 -13 , 1 x 10 -12 , 1 x 10 -11 , 1 x 10 -10 , 5 x 10 -10 , 1 x 10 -9 , 5 x 10 -9 , 1 x 10 -8 , 3 x 10 -8 , 5 x 10 -8 , 7 x 10 -8 mol / L) while keeping the amount of NPs added at 1 x 10 -7 mol / L, and the precise quantitative analysis of trace ZENs was performed. Similarly, the fluorescence recovery graph after the addition of QDs-NPs to ZENs is shown in Figure 4(A) shows that with the increase of the concentration of ZENs, the fluorescence of the QDs-NPs system shows a trend of continuous increase, and the linear fitting analysis is carried out on the concentration of ZENs Figure 4 B-C), Figure 4 B is a curve graph of the fluorescence change of the QDs-NPs system with the change of the concentration of ZENs, Figure 4 C is a linear fitting graph of the fluorescence change of the QDs-NPs system and log(ZENs concentration).

[0071] (II) Stability and anti-interference of the fluorescence switch sensor

[0072] In order to ensure the stability of the fluorescence switch sensor, the fluorescence response of the sensor under different pH conditions is tested, and the buffer solution (NaOH-HCl solution) with pH 5-10 is configured, that is, the second group: pH buffer solution (800 μL), cadmium telluride quantum dots (100 μL, 3×10 -10 mol / L) and nanometer porphyrin (100 μL, 1×10 -6 mol / L); the third group is: pH buffer solution (730 μL), cadmium telluride quantum dots (100 μL, 3×10 -10 mol / L), nanometer porphyrin (100 μL, 1×10 -6 mol / L) and zearalenone (70 μL, 1×10 -6 mol / L).

[0073] The results are shown in Figure 5 (A), within the range of pH 5-10, both the QDs and the QDs-NPs fluorescence switch sensor can maintain good fluorescence response stability.

[0074] Subsequently, in order to test the anti-interference performance of the composite sensor for ZENs detection, common metal ions and amino acids (Mg -7 , Na 2+ , K + , Ca + , Fe 2+ , Gly, Glu, Ala) with high concentration (1×10 3+ mol / L) are used as interference components to be added to the detection system. As shown in Figure 5 (B), even if high-concentration interference components are added to the detection system, the fluorescence switch sensor can still produce stable fluorescence response to trace ZENs.

[0075] (III) Selectivity of the fluorescence switch sensor

[0076] The other samples to be detected in the control group experiment are replaced with samples with a concentration of 1×10 -6mol / L of other mycotoxins. The small molecule compounds identified in this example include: zearalenols (ZELs), T-2 toxins (T-2s), ochratoxin A (OTA), fumonisins (FUMs), aflatoxins (AFLs), and deoxynivalenol (DON), all at a concentration of 1 x 10 -6 mol / L. Other mycotoxins selective comparison bar graphs are shown in FIG. 2, which shows that even ZELs, which differ by only one group in structure, do not cause recovery of the fluorescence of the QDs, indicating that the fluorescence switch sensor constructed in the present application has good selectivity. Figure 6

[0077] Example 3

[0078] The fluorescence switch sensor constructed in the present application can achieve identification of compounds in grain substrates at a concentration of 10 -12 mol / L, based on identification of pure substances of ZENs small molecule compounds. In this example, the different concentrations of zearalenone in Example 2 were replaced with corn, soybeans, cereal, millet, and rice. The grains were ground and soaked, and were configured at a concentration of 10 -8 mol / L, 10 -10 mol / L, and 10 -12 mol / L, respectively.

[0079] Similarly, timing was started after the last reaction reagent was added, and the fluorescence emission spectrum of the system was recorded after 5 min, and all data were repeated 3 times. The above fluorescence comparison bar graphs are shown in FIG. 3. Spiked samples were prepared by adding different concentrations of ZENs to actual samples (corn, rice, soybeans, etc.), and the recovery rate of ZENs was used as an evaluation index to determine the accuracy of quantitative analysis. The results are shown in Table 2, which shows that even in real food samples, the sensor can still achieve accurate detection of trace amounts of ZENs, with a recovery rate of 98.5%-103.3%. Figure 7

[0080] Table 2 Recovery rate of the fluorescence switch sensor for detection of ZEAs in real food samples

[0081]

[0082]

[0083] Example 4

[0084] The fluorescence switch sensor constructed in the present application was used to detect different concentrations (1 x 10 -15 , 1 x 10 -14 , 1 x 10 -13 , 1 x 10 -12 , 1 x 10 -11 , 1 x 10​​-10 1×10 -9 1×10 -8 After ZENs (mol / L) and other mycotoxins were dropped onto a 96-well plate, the colorimetric results were visualized under UV light, as shown in the figure below. Figure 8 As shown, the sensor exhibits excellent fluorescence visualization performance. The constructed fluorescent switch sensor demonstrates good sensitivity and selectivity for other types of mycotoxins and similar zearalenones. By dropping the QDs-NPs sensor onto a 96-well plate, the visual detection of trace ZENs can be achieved.

[0085] Example 5

[0086] The fluorescent switch sensor constructed in this invention exhibits excellent fluorescence visualization performance, so its visualization and detection performance for ZENs was further investigated. By loading the sensor onto a portable paper-based chip (which can be understood as a piece of paper), a visual paper-based sensor was constructed, and its visualization and color development results for ZENs are as follows: Figure 9 As shown. Even after being loaded onto a paper-based chip, the sensor still retains good selectivity and sensitivity. When a ZENs concentration of 1×10⁻⁶ is added... -12 A noticeable color change occurs at concentrations of mol / L, and it exhibits good selectivity for other types of mycotoxins and similar zearalenones. Figure 9 In the last image, the concentration of different mycotoxins to be tested is 70 nM. By loading the QDs-NPs sensor onto a portable paper-based chip, the visual detection of trace ZENs can be achieved.

[0087] In summary, the fluorescent switch sensor based on quantum dots and nanoporphyrin prepared in this invention can identify trace amounts of ZENs in food and has high sensitivity and high selectivity.

[0088] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a quantum dot-nanoporphyrin based fluorescent switch sensor, characterized by: The method comprises the following steps: (1) synthesis of CdTe QDs Dissolve cadmium chloride and mercaptosuccinic acid in ultrapure water, stir, adjust pH to alkaline, stir at room temperature under nitrogen atmosphere, inject sodium tellurite aqueous solution, then add sodium borohydride aqueous solution, continue to stir under nitrogen atmosphere, and hydrothermal reaction at 200℃ for 30 min to obtain CdTe QDs; (2) synthesis of nano-porphyrin Heat water bath to 40℃, dissolve 5,10,15,20-tetra(4-nitrophenyl) porphyrin in DMF, and drop into cetyltrimethylammonium bromide aqueous solution drop by drop, and slowly stir to obtain nano-porphyrin solution; (3) synthesis of quantum dot-nano-porphyrin fluorescent switch sensor Add nano-porphyrin solution to CdTe QDs to obtain the fluorescent switch sensor.

2. The method of claim 1, wherein: In step (1), the molar ratio of cadmium chloride and mercaptosuccinic acid is 0.5-1.5:0.8-2.0, the mass-volume ratio of cadmium chloride to ultrapure water is 1:200-300, and the mass-volume ratio of mercaptosuccinic acid to ultrapure water is 1:200-330.

3. The method of claim 1, wherein: In step (1), the mass-volume ratio of sodium tellurite to water is 1:20-30, and the mass-volume ratio of sodium borohydride to water is 1:12-25.

4. The method of claim 1, wherein: In step (2), the concentration of the 5,10,15,20-tetra(4-nitrophenyl)porphyrin is 6 x 10 -4 -9 x 10 -4 mol / L, and the concentration of the aqueous solution of cetyltrimethylammonium bromide is 2-7 mmol / L.

5. The method of claim 1, wherein: In step (3), the concentration of the nanopyrrole is 2 x 10 -9 -1 x 10 -7 mol / L, and the concentration of the CdTe QDs is 8 x 10 -9 -3 x 10 -8 mol / L.

6. The production method according to claim 1 or 5, characterized by: In step (3), the volume ratio of CdTe QDs to nano-porphyrin is 1:3-3:

1.

7. A quantum dot-nano-porphyrin-based fluorescent switch sensor prepared by the preparation method of any one of claims 1-6.

8. The application of the quantum dot-nano-porphyrin-based fluorescent switch sensor of claim 7 in detecting zearalenone.

9. Use according to claim 8, characterized in that: The minimum detection limit of the fluorescent switch sensor for zearalenone is 6 x 10 -15 mol / L.

10. A visual paper-based sensor characterized by: A visual paper-based sensor is constructed by loading the quantum dot-nano-porphyrin-based fluorescent switch sensor of claim 7 on a portable paper-based chip.

Images