Double-signal sensor for detecting zearalenone toxin as well as construction method and application of double-signal sensor

Abstract

The invention relates to a dual-signal sensor for detecting zearalenone toxin as well as a construction method and application of the dual-signal sensor. The method comprises the following steps: incubating functionalized cDNA (complementary deoxyribonucleic acid) and a COF-Au solution to obtain COF-Au-cDNA; the preparation method comprises the following steps: mixing an aptamer apt of zearalenone toxin with Fe3O4 (at) SiO2-QD, and then adding 1-ethyl-3-(3-dimethylaminopropyl) diimine hydrochloride and N-hydroxysuccinimide for incubation, so as to obtain Fe3O4 (at) SiO2-QD-apt; and carrying out mixed incubation on the obtained COF-Au-cDNA and the obtained Fe3O4 (at) SiO2-QD-apt, so as to obtain the double-signal sensor for detecting the zearalenone toxin. The dual-signal sensor can perform UV-Vis signal and fluorescence signal detection on zearalenone toxin, solves the problem of unstable result caused by influence of a single signal source, and has high sensitivity and specificity.

Description

Technical Field

[0001] The present invention relates to the technical field of food analysis and detection, and in particular to a dual-signal sensor for detecting zearalenone toxin, and a construction method and application thereof. Background Art

[0002] Zearalenone (ZEN), also known as F-2 toxin, is a non-steroidal estrogen-like mycotoxin, mainly produced by Fusarium graminearum, Fusarium graminearum, Fusarium thunbergii and other Fusarium thunbergii. ZEN toxin widely contaminates various cereal crops and foods such as wheat, corn, barley, sorghum, and soybeans. The molecular structure of ZEN is similar to that of estrogen, so it can cause significant reproductive toxicity. ZEN can exert estrogenic activity, and estrogen also plays an important regulatory role in the development and maintenance of the immune system, so ZEN can cause immunotoxicity. ZEN can also cause toxic effects on organs such as the kidneys, intestines, and liver.

[0003] Current methods for toxin detection include high performance liquid chromatography (HPLC), liquid chromatography tandem mass spectrometry (LC-MS), capillary electrophoresis (CE), immunological methods, etc. Although these methods are widely used, they have some defects, such as complex HPLC pretreatment, expensive equipment, and high detection cost; immunological methods are susceptible to interference and prone to false positives. Therefore, the development of a rapid, efficient, and low-cost method for detecting zearalenone toxins is of great practical significance.

[0004] Colorimetric analysis is an optical detection technology that uses color change as an output signal. The detection results can be qualitatively analyzed by visual observation or quantitatively analyzed by optical measurement equipment. The colorimetric detection method can cause the color of the chromogenic substrate to change through an enzyme-catalyzed reaction. In the colorimetric analysis based on enzymatic reactions, nanozymes are inexpensive, stable, and durable in storage, and they dominate in biosensing applications, such as precious metal nanoparticles, Fe3O4 nanoparticles, metal organic frameworks (MOFs), covalent organic frameworks (COFs), etc. At present, some colorimetric sensing detection methods for zearalenone toxin have also been developed. For example, Sun et al. used ZEN aptamers to inhibit the peroxidase mimicry activity of AuNPs to detect ZEN in corn and corn oil. The detection range was 10-250 ng / mL and the LOD value was 10 ng / mL (Sun SM, Zhao R, Feng SM and Xie YL. Colorimetric zearalenone assay based on the use of an aptamer and of gold nanoparticles with peroxidase-like activity. Microchimica Acta, 2018, 185 (12).). However, AuNPs have poor stability and are easily affected by other interferences and aggregated, resulting in false positive results.

[0005] Fluorescence is a process of absorbing short-wave energy and emitting light when returning to the ground state. When light is irradiated on a molecule, some electrons become unstable excited states, which tend to lose energy and return to the ground state. The light energy released in this process is fluorescence, and the technology of using fluorescence signals to detect and identify specific molecules or ions is called fluorescence analysis technology. In recent years, sensors based on fluorescence analysis technology have high sensitivity, strong selectivity, simple operation, and low cost, and have been widely used in the fields of biosensors, environmental monitoring, food safety, and medical diagnosis. Bondarenko, AP et al. used a fluorescent labeled immunosorbent assay of liposomes loaded with water-soluble and water-insoluble QDs, and the detection limit of ZEN was 20pg / mL (Bondarenko AP and Eremin S A. Determination of zearalenone and ochratoxin amycotoxins in grain by fluorescence polarization immunoassay. Journal of Analytical Chemistry, 2012, 67 (9): 790-794). However, this method requires the use of antibodies and fluorescent labels, which is expensive.

[0006] Currently, covalent organic frameworks (COFs) have attracted much attention in detection applications due to their unique structures and properties. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a dual-signal sensor for detecting zearalenone toxin, as well as a construction method and application. The present invention utilizes the porous structure of COF to synthesize a COF-Au composite material with nanoenzyme properties. After modifying the nucleic acid chain, it is connected with Fe3O4@SiO2@QD-apt through the principle of base complementary pairing. After the target is added, the aptamer preferentially binds to the target, the assembly disintegrates, the quenching degree of the fluorescence intensity at the magnetic bead end is weakened, the COF-Au in the supernatant increases, and the peroxidation effect is enhanced. Therefore, dual-mode detection can be achieved by using the supernatant to catalyze the TMB (3,3′,5,5′-tetramethylbenzidine) reaction to measure UV-Vis and precipitate to measure fluorescence.

[0008] The present invention is achieved through the following technical solutions:

[0009] The first object of the present invention is to provide a method for constructing a dual-signal sensor for detecting zearalenone toxin, comprising the following steps:

[0010] (1) incubating the functionalized cDNA with a COF-Au solution to obtain COF-Au-cDNA;

[0011] (2) After mixing the aptamer of zearalenone toxin apt with Fe3O4@SiO2-QD, 1-ethyl-3-(3-dimethylaminopropyl) diimide hydrochloride and N-hydroxysuccinimide were added for incubation to obtain Fe3O4@SiO2-QD-apt;

[0012] (3) The COF-Au-cDNA obtained in step (1) and the Fe3O4@SiO2-QD-apt obtained in step (2) are mixed and incubated to obtain a dual-signal sensor for detecting zearalenone toxin.

[0013] In one embodiment of the present invention, in step (1), the nucleotide sequence of the functionalized cDNA is: 5'-SH-(CH2)6-CAGATAGTAATGTACCATAGATAG-3' (SEQ ID NO. 1).

[0014] In one embodiment of the present invention, in step (1), the COF-Au is prepared by the following method:

[0015] Chloroauric acid is added dropwise to the alcohol solution of COF, and the mixture is stirred under ice bath; then the alcohol solution of sodium borohydride is added dropwise and stirred to react.

[0016] In one embodiment of the present invention, the synthesis of the COF is as follows: 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-dimethoxyterephthalaldehyde (DMTP) are added to a 1,4-dioxane-n-butanol-methanol co-solvent system. After ultrasonic treatment, an acetic acid aqueous solution is added dropwise and allowed to stand at room temperature. Subsequently, an acetic acid aqueous solution is added and heated. Finally, the product is cooled to room temperature, washed, and vacuum dried.

[0017] In one embodiment of the present invention, in step (2), the nucleotide sequence of the aptamer apt of the zearalenone toxin is: 5'-NH2-(CH2)6-TCATCTATCTATGGTACATTACTATCTGTAATGTGATATG-3' (SEQ ID NO. 2).

[0018] In one embodiment of the present invention, in step (2), the Fe3O4@SiO2-QD is prepared by the following method:

[0019] The quantum dots were obtained by incubating with 1-ethyl-3-(3-dimethylaminopropyl)diimide hydrochloride overnight and then reacting with an aqueous solution of Fe3O4@SiO2-NH2.

[0020] In one embodiment of the present invention, the Fe3O4@SiO2-NH2 is prepared by the following method:

[0021] After the alcohol solution of Fe3O4 nanoparticles was ultrasonically treated with water and ammonia, ethyl orthosilicate was slowly added and stirred for reaction. The product was separated by a magnet, washed and dried to obtain Fe3O4@SiO2 nanoparticles.

[0022] The obtained Fe3O4@SiO2 nanoparticles are dispersed in ethanol and (3-aminopropyl)triethoxysilane, stirred at room temperature, washed and dried to obtain the Fe3O4@SiO2-NH2.

[0023] In one embodiment of the present invention, in step (3), the volume ratio of the COF-Au-cDNA to the Fe3O4@SiO2-QD-apt is 4:1 to 1:1;

[0024] And / or, the incubation condition is 30° C. to 40° C. for 1 h to 3 h.

[0025] In one embodiment of the present invention, it also includes establishing a standard curve for detecting zearalenone toxin:

[0026] Take the dual-signal sensor for detecting zearalenone toxin, add different concentrations of ZEN solution for incubation, and separate by magnetic absorption; aspirate the supernatant, add acetic acid-sodium acetate buffer, H2O2, and 3,3′,5,5′-tetramethylbenzidine (TMB) solution to react and measure UV-Vis. Wash the precipitate three times and resuspend it in water, and measure the emission spectrum at an excitation wavelength of 340nm. Take the logarithm of the zearalenone toxin concentration as the horizontal axis and the UV-Vis signal / fluorescence signal value as the vertical axis to determine the standard curve.

[0027] The second object of the present invention is to provide a dual-signal sensor for detecting zearalenone toxin obtained by the construction method.

[0028] The third object of the present invention is to provide the application of the dual-signal sensor in detecting zearalenone toxin.

[0029] In one embodiment of the present invention, the concentration of the zearalenone toxin is 0.1 μg / kg to 10000 μg / kg.

[0030] The present invention synthesizes a COF-Au composite material by in-situ reduction of gold on the basis of COF. The COF substrate is spherical with uniform size, and the gold nanoparticles do not destroy its original structure. The nucleic acid chain (aptamer complementary chain) modified with -SH is connected to COF-Au through a gold-sulfur bond, and an assembly structure can be formed with the Fe3O4@SiO2-QD material modified with the aptamer, and the experiment is carried out as a signal probe.

[0031] The present invention coats the magnetic beads (Fe3O4) with a silicon layer (SiO2) after synthesis, and connects red quantum dots (QD) after amino modification. The carboxyl groups on the quantum dots can condense with the amino groups on the aptamer, thereby synthesizing a capture fluorescent probe with specific recognition of zearalenone toxin.

[0032] The present invention connects COF-Au and Fe3O4@SiO2-QD through complementary base pairing to form an assembly. The characteristics of the assembly are: COF-Au has a quenching effect on the fluorescence signal of Fe3O4@SiO2-QD, and after the assembly is formed, the fluorescence signal of the system decreases; after the target is added, the aptamer preferentially binds to it, and COF-Au falls from Fe3O4@SiO2-QD. Through magnetic separation, the COF-Au in the supernatant increases with the increase of the target concentration, and the precipitated fluorescence signal recovers with the addition of the target.

[0033] The above technical solution of the present invention has the following advantages compared with the prior art:

[0034] The present invention constructs a Fe3O4@SiO2-QD-apt-cDNA-COF-Au assembly and performs dual signal detection on zearalenone toxin. This method can eliminate the problem of unstable results caused by the influence of a single signal source, and has high sensitivity and specificity; on the one hand, COF-Au is easy to regulate and has good stability, avoiding the shortcomings of harsh conditions for the use of natural enzymes and easy inactivation; on the other hand, connecting quantum dots with Fe3O4@SiO2 that can be separated by magnetic attraction not only avoids the quenching effect of Fe3O4 on quantum dots, but also successfully achieves rapid separation. COF-Au acts as a quencher of QD to regulate the change of fluorescence intensity, and as a catalyst for colorimetric signal determination to control UV-Vis signals. This method is suitable for the fields of food safety and analytical detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0036] Figure 1 1 is a transmission electron microscope characterization image (TEM) of COF (A) and COF-Au (B) in Example 1 of the present invention;

[0037] Figure 2 It is the transmission electron microscope characterization (TEM) image of Fe3O4 (A), Fe3O4@SiO2 (B), and Fe3O4@SiO2-QD (C) in Example 1 of the present invention;

[0038] Figure 3 1 is a fluorescence spectra of different concentrations of zearalenone toxin in Example 1 of the present invention (A); and a corresponding standard curve (B);

[0039] Figure 4 The UV-visible spectra of different concentrations of zearalenone toxin in Example 1 of the present invention (A) and the corresponding standard curve (B); Figure 5 It is the fluorescence intensity under different types of toxins in the present invention (A); UV-Vis value under different types of toxins (B). DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0041] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0042] Example 1 Construction of Fe3O4@SiO2-QD-apt-cDNA-COF-Au assembly

[0043] In order to further verify the detection ability of the detection method prepared by the present invention for zearalenone toxin, the present invention is described using Fe3O4@SiO2-QD-apt-cDNA-COF-Au assembly as an example:

[0044] Step 1) Preparation of COF-Au-cDNA:

[0045] Synthesis of COF: 10.5 mg of 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 8.7 mg of 2,5-dimethoxyterephthalaldehyde (DMTP) were added to 4.5 mL of 1,4-dioxane-n-butanol-methanol (v / v / v, 4:4:1) co-solvent system. After ultrasonic treatment for 20 min, 0.050 mL of 12 mol / L acetic acid aqueous solution was added dropwise and allowed to stand at room temperature for 2 h. Subsequently, 0.45 mL of 12 mol / L acetic acid aqueous solution was added, and the solution was heated at 70 ° C for 24 h. Finally, the product was cooled to room temperature, and the resulting COF was washed with tetrahydrofuran and acetone, and then dried in vacuo at 60 ° C.

[0046] Synthesis of COF-Au: The synthesized COF (60 mg) was suspended in 30 mL of methanol and the pH was adjusted to about 4 with hydrochloric acid. 320 μL of 1% HAuCl4·4H2O was added dropwise to the mixture under vigorous stirring, and then the mixture was continuously stirred for 5 hours under an ice bath. After that, 2 mL of freshly prepared NaBH4 methanol solution (0.20 mol / L) was added dropwise under the same synthesis conditions and stirred for another 3 hours. The resulting precipitate was centrifuged and washed with methanol. Finally, the yellow powder was dried in a vacuum oven at 60°C for 12 hours.

[0047] Nucleic acid functionalized COF-Au: 360 μL of cDNA (final concentration 10 μM) was activated at 95°C for 10 min, and after cooling, 30 μL of TCEP solution (1 mM) was added and suspended in the dark for 2 h to reduce the thiol group modified at the end of the aptamer. 50 μL of the above activated cDNA was added to 1 mL of 1 mg / mL COF-Au solution and incubated overnight to bond it to the surface of COF-Au nanocomposite particles through Au-S chemical bonds. COF-Au-cDNA was obtained and placed in the dark at 4°C for use.

[0048] Figure 1 Transmission electron microscopy (TEM) images of COF (A) and COF-Au (B); Figure 1 It can be seen that COF presents a uniform spherical shape and AuNPs are uniformly loaded on COF.

[0049] Step 2) Synthesis of Fe3O4@SiO2-QD-apt:

[0050] Synthesis of Fe3O4: FeCl3·6H2O (0.985 g), trisodium citrate (dihydrate, 0.390 g) and anhydrous sodium acetate (2.0 g) were dissolved in 30 mL of ethylene glycol and stirred at room temperature until a transparent solution was formed. The resulting solution was then transferred to a polytetrafluoroethylene reactor and heated at 200°C for 12 h. Subsequently, the brown product was separated by an external magnetic field and washed alternately with ultrapure water and ethanol several times. Finally, the nanoparticles were dried under vacuum at 60°C to obtain a solid powder for further use.

[0051] Synthesis of Fe3O4@SiO2: Fe3O4 nanoparticles (150 mg) were dispersed in 280 mL of ethanol solution, and then 70 mL of ultrapure water and 5.0 mL of ammonia water were added. After sufficient ultrasonic treatment, 6.0 mL of tetraethyl orthosilicate (TEOS) was slowly added to the above solution under vigorous mechanical stirring, and the drop rate was about 2 mL / min. After dropping, it was continuously stirred at room temperature for 10 h. The brown product was separated with a magnet, and after washing with ultrapure water and ethanol several times, the product was vacuum dried at 60 ° C to obtain solid powder Fe3O4@SiO2 nanoparticles. Fe3O4@SiO2 nanoparticles (200 mg) were dispersed in ethanol (45 mL) and APTES (3 mL) and stirred at room temperature for 12 h. Then, the product was completely washed with ethanol and dried in vacuo at 60°C to obtain Fe3O4@SiO2-NH2; Fe3O4@SiO2-NH2 was dispersed in water to obtain Fe3O4@SiO2-NH2 solution.

[0052] Synthesis of QD: Add 31.9 mg of tellurium powder and 50 mg of NaBH4 to a centrifuge tube. Then add 2 mL of ultrapure water, pass nitrogen in an ice bath for 10 minutes, and seal the reaction until the solution changes from black to a purple transparent solution to obtain solution A. Then, dissolve 114.2 mg of CdCl2·2.5H2O in 100 mL of water. Add 130 μL of 3-mercaptopropionic acid (MPA), adjust the pH to 8.5 with 1 mol / L NaOH to obtain solution B, pass nitrogen for 10 minutes, and seal. Quickly add 2 mL of solution A to solution B, heat to 115°C, reflux for 11 hours to obtain red CdTe QDs, and store at 4°C for later use.

[0053] Synthesis of Fe3O4@SiO2-QD: Take 5 mL of the above quantum dots, add 1.25 mL of 1-ethyl-3-(3-dimethylaminopropyl) diimide hydrochloride (EDC, 40 mg / mL), incubate at 4°C overnight, then add 1.5 mL of the above incubated mixture to 1 mL of Fe3O4@SiO2-NH2 solution (1 mg / mL), then add water to 4 mL, react for 4 hours, separate by magnetic absorption, wash three times with water, resuspend in 2 mL of water, and measure the emission spectrum under 340 nm excitation.

[0054] Nucleic acid functionalized Fe3O4@SiO2-QD: 80 μL, 10 μM ZEN aptamer was mixed with 1 mL Fe3O4@SiO2-QD, and then 20 μL freshly prepared EDC (40 mg / mL) and 20 μL NHS (20 mg / mL) were added to the mixture and incubated for 2 h. After incubation, the mixture was washed three times with BB buffer at pH 7.4 to remove excess aptamer. The precipitate was dispersed in BB buffer to obtain Fe3O4@SiO2-QD-apt.

[0055] Figure 2 The transmission electron microscopy (TEM) images of Fe3O4 (A), Fe3O4@SiO2 (B), and Fe3O4@SiO2-QD are shown respectively. Figure 2 It can be seen that Fe3O4 is spherical with uniform size, the silicon layer is evenly coated on the outer surface of Fe3O4 with a thickness of about 30nm, and QDs are evenly loaded on the silicon layer.

[0056] Step 3) Preparation of Fe3O4@SiO2-QD-apt-cDNA-COF-Au assembly:

[0057] Take 200 μL of Fe3O4@SiO2-QD-apt prepared in step 2) and 400 μL of COF-Au-cDNA prepared in step 1) and mix them, incubate at 37°C for 2 h, separate by magnetic absorption, wash three times with BB buffer and resuspend to 180 μL.

[0058] Step 4) Establishing a standard curve for detecting zearalenone toxin:

[0059] Take 180 μL of the assembly prepared in step 3) above, add 20 μL of ZEN solution of different concentrations, incubate for 1 hour, and separate by magnetic attraction. Take 100 μL of supernatant, add 600 μL HAc-NaAc buffer (pH 3.6, 1.0M), 100 μL H2O2, 100 μL TMB solution, dilute to 1 mL, react at 37°C for 25 minutes, and then measure UV-Vis. Wash the precipitate three times and resuspend it in 400 μL water, and measure the emission spectrum at an excitation wavelength of 340 nm. Take the logarithmic value of the zearalenone toxin concentration as the horizontal axis, and the UV-Vis signal / fluorescence signal value as the vertical axis to determine the standard curve.

[0060] Figure 3 The fluorescence spectra of zearalenone toxin at different concentrations (A) and the corresponding standard curve (B); Figure 4 The UV-Vis images (C) and the corresponding standard curve (D) under different concentrations of zearalenone toxin. Figure 3 and Figure 4 It can be seen that when fluorescence is used as the signal source, the linear range of the detection method is 0.1-10000 μg / kg, and the LOD is 0.09 μg / kg; when UV-Vis is used as the signal source, the linear range of the detection method is 0.5-10000 μg / kg, and the LOD is 0.36 μg / kg.

[0061] Example 2 Specificity Test

[0062] Take 180 μL of the assembly prepared in step 3) of Example 1, add 20 μL of different types of toxins (aflatoxin B1 (AFB1), aflatoxin G1 (AFG1), ochratoxin (OTA), deoxynivalenol (DON), ZEN and a mixed solution of the above toxins) and incubate for 1 hour. After magnetic separation, the determination is carried out according to step 4) of Example 1.

[0063] Figure 5 The fluorescence intensity under different types of toxins (A); UV-Vis value under different types of toxins (B). Figure 5 It can be seen that this detection method has good specificity for ZEN.

[0064] Example 3 Determination of the content of zearalenone in real samples

[0065] Wheat flour and corn were selected as actual samples, and the test results after spiked wheat flour and corn samples were shown in Table 1:

[0066] Table 1 Determination of ZEN in actual samples by the proposed method

[0067]

[0068] As can be seen from Table 1, this detection method has high accuracy in the detection of actual samples and has good practical applicability in food.

[0069] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for constructing a dual-signal sensor for detecting zearalenone toxin, characterized in that: The following steps are involved: (1) incubating the functionalized cDNA with a COF-Au solution to obtain COF-Au-cDNA; (2) After mixing the aptamer of zearalenone toxin apt with Fe3O4@SiO2-QD, 1-ethyl-3-(3-dimethylaminopropyl) diimide hydrochloride and N-hydroxysuccinimide were added for incubation to obtain Fe3O4@SiO2-QD-apt; (3) The COF-Au-cDNA obtained in step (1) and the Fe3O4@SiO2-QD-apt obtained in step (2) are mixed and incubated to obtain a dual-signal sensor for detecting zearalenone toxin.

2. The construction method according to claim 1, characterized in that: In step (1), the nucleotide sequence of the functionalized cDNA is: 5'-SH-(CH2)6-CAGATAGTAATGTACCATAGATAG-3'.

3. The construction method according to claim 1, characterized in that: In step (1), the COF-Au is prepared by the following method: Chloroauric acid is added dropwise to the alcohol solution of COF, and the mixture is stirred under ice bath; then the alcohol solution of sodium borohydride is added dropwise and stirred to react.

4. The construction method according to claim 1, characterized in that: In step (2), the nucleotide sequence of the aptamer apt of the zearalenone toxin is: 5'-NH2-(CH2)6-TCATCTATCTATGGTACATTACTATCTGTAATGTGATATG-3'.

5. The construction method according to claim 1, characterized in that: In step (2), the Fe3O4@SiO2-QD is prepared by the following method: The quantum dots were obtained by incubating with 1-ethyl-3-(3-dimethylaminopropyl)diimide hydrochloride overnight and then reacting with an aqueous solution of Fe3O4@SiO2-NH2.

6. The construction method according to claim 5, characterized in that: The Fe3O4@SiO2-NH2 is prepared by the following method: After the alcohol solution of Fe3O4 nanoparticles was ultrasonically treated with water and ammonia, ethyl orthosilicate was slowly added and stirred for reaction. The product was separated by a magnet, washed and dried to obtain Fe3O4@SiO2 nanoparticles. The obtained Fe3O4@SiO2 nanoparticles are dispersed in ethanol and (3-aminopropyl)triethoxysilane, stirred at room temperature, washed and dried to obtain the Fe3O4@SiO2-NH2.

7. The construction method according to claim 1, characterized in that: In step (3), the volume ratio of the COF-Au-cDNA to the Fe3O4@SiO2-QD-apt is 4:1 to 1:1; And / or, the incubation condition is 30° C. to 40° C. for 1 h to 3 h.

8. A dual-signal sensor for detecting zearalenone toxin obtained by the construction method according to any one of claims 1 to 7.

9. Use of the dual signal sensor according to claim 8 in detecting zearalenone toxin.

10. The use according to claim 9, characterized in that: The concentration of the zearalenone toxin is 0.1 μg / kg to 10000 μg / kg.

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