Method for detecting AFB1 by LEG / titanium carbide-based aptamer sensor

Abstract

The invention provides a method for detecting AFB1 by using an LEG / titanium carbide-based aptamer sensor. The method comprises the following steps: firstly, constructing the LEG / titanium carbide-based aptamer sensor, mixing an LEG suspension and a Ti3C2 MXene material to prepare an LEG / Ti3C2 MXene nano material, then modifying the LEG / Ti3C2 MXene nano material on ITO (Indium Tin Oxide) to construct a sensitive interface of the AFB1, and then modifying Fc-aptamer, BSA (Bovine Serum Albumin) and MB-cDNA layer by layer to construct the sensitive interface for detecting the AFB1. And then the sensor is used for establishing a working curve and detecting the AFB1. The sensor is simple in preparation process, good in reproducibility, high in selectivity and good in stability, ultra-sensitive detection of trace AFB1 in peanuts and corns can be achieved, the sensor has high sensitivity and a wide linear range within 0.0001-100 ng / mL, and the detection line is as low as 0.041 pg / mL.

Description

Technical Field

[0001] The present invention relates to the technical field of food safety monitoring, and in particular to a method for detecting AFB1 using a LEG / titanium carbide-based aptamer sensor. Background Art

[0002] The main methods for detecting trace aflatoxin B1 (AFB1) residues in peanuts and corn are high performance liquid chromatography, high performance liquid chromatography-fluorescence detection, liquid chromatography-mass spectrometry and enzyme-linked immunosorbent assay, all of which show good sensitivity and selectivity. However, the equipment and instrument maintenance cost of the former is high, the operation requires professionally trained personnel, the results need to be interpreted, the sample pretreatment time is long, and the instrument is very sensitive to changes in sample composition and quality. These reasons limit the use of this method to well-equipped laboratories. The sensitivity of the latter is easily interfered and may cross-react with other substances, resulting in false positives. Therefore, establishing a simple, rapid and highly sensitive aflatoxin B1 analysis method is an important scientific issue that needs to be solved urgently. Summary of the invention

[0003] In view of this, the present invention aims to propose a method for detecting AFB1 using a LEG / titanium carbide-based aptamer sensor. The LEG / titanium carbide-based aptamer sensor is simple to manufacture, has good stability, low sensitivity, and excellent specificity, and exhibits a good linear relationship in the range of 0.0001-100 ng / mL, thereby realizing the detection of AFB1.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows: A method for detecting AFB1 using a LEG / titanium carbide-based aptamer sensor, the method comprising the following steps: S1. Preparation of LEG / Ti3C2-based aptasensor First, LEG suspension and Ti3C2MXene material were prepared respectively, and then the LEG suspension and Ti3C2MXene material were mixed by ultrasound to obtain LEG / Ti3C2MXene nanomaterials, and then the LEG / Ti3C2MXene nanomaterials were modified on ITO to construct a sensitive interface for AFB1, and then Fc-aptamer, BSA, and MB-cDNA were modified layer by layer to construct a sensitive interface for detecting AFB1, and finally the LEG / Ti3C2-based aptamer sensor MB-cDNA / BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO was obtained; S2. Detection of AFB1 S21. Draw the working curve of AFB1 The AFB1 standard solution was added to the LEG / Ti3C2-based aptamer sensor for incubation, and then the sensor was detected by differential pulse voltammetry. Fc and I MB The working curve is drawn based on the change ratio of S22. Detection of AFB1 in the sample to be tested The sample to be tested is dripped onto the LEG / Ti3C2-based aptamer sensor for incubation. Under the same conditions as step S21, the current value is recorded, and the concentration of AFB1 in the sample to be tested is calculated based on the working curve obtained in step S21.

[0005] In the present invention, after the graphite powder is subjected to ultrasonic exfoliation, not only a single layer can be formed, but also the single layer flakes can be ultrasonically converted into smaller flakes to form a charged material, which can react with Ti3C2MXene to form a stable mixed material. However, the graphite powder itself has a large particle size, is in a multi-layer state, and is easy to precipitate, which is not conducive to the preparation of LEG / Ti3C2MXene nanomaterials.

[0006] Further, the specific method for preparing the LEG suspension is: (1) dispersing graphite powder in a co-solvent of N,N-dimethylformamide and deionized water; (2) Using ultrasound to deeply delaminate graphite sheets; (3) The dispersion was centrifuged to remove unexfoliated graphite, and two-thirds of the supernatant was collected as the LEG suspension.

[0007] Furthermore, in step (1), the solid-liquid ratio of graphite powder to co-solvent is 1:100 g / ml, and the volume ratio of N,N-dimethylformamide to deionized water is 7:3; In step (2), ultrasonication is performed for 48±5 hours at a temperature of 40-50°C; In step (3), the centrifugation conditions are: 4000±500 rpm, 40±5 min.

[0008] Further, the specific method for preparing Ti3C2MXene material is: (1) Dispersing Ti3AlC2 powder and lithium fluoride in hydrochloric acid, stirring, and then washing the mixture with deionized water to collect a solid sample; (2) Add the solid sample to deionized water for ultrasonic treatment; (3) The final product Ti3C2Mxene material is obtained after freeze drying.

[0009] Furthermore, in step (1), the mass ratio of Ti3AlC2 powder to lithium fluoride is 1:3.2, the solid-liquid ratio of Ti3AlC2 powder to lithium fluoride to hydrochloric acid is 21:200 g / ml, the concentration of hydrochloric acid is 9 M, and stirring is performed at room temperature for 26 hours; In step (2), ultrasonic treatment is performed for 6±1 hours; In step (3), freeze-drying is performed for 24-48 hours.

[0010] Further, the specific method for preparing the LEG / Ti3C2-based aptamer sensor is as follows: (1) Ultrasonic mixing of the prepared LEG suspension and Ti3C2MXene material to obtain LEG / Ti3C2MXene nanomaterials; (2) Select ITO as the working electrode and clean it with acetone, ethanol, and deionized water in sequence to remove surface dirt; (3) Dry the clean ITO in an oven, drop LEG / Ti3C2MXene nanomaterials on the surface, dry at room temperature, and then rinse with deionized water to obtain LEG / Ti3C2MXene / ITO; (4) Adding aflatoxin B1 aptamer Fc-aptamer onto LEG / Ti3C2MXene / ITO, drying at room temperature after incubation, and then rinsing the surface with deionized water to obtain Fc-aptamer / LEG / Ti3C2MXene / ITO; (5) bovine serum albumin (BSA) was added dropwise onto Fc-aptamer / LEG / Ti3C2MXene / ITO, dried at room temperature, and then rinsed with deionized water to obtain BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO; (6) The aptamer complementary chain MB-cDNA was added dropwise onto BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO, incubated at room temperature and rinsed with deionized water to obtain MB-cDNA / BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO, and finally the LEG / Ti3C2-based aptamer sensor MB-cDNA / BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO for detecting AFB1 was obtained.

[0011] Furthermore, in step (1), the Ti3C2Mxene material is first dissolved in a solvent to form a solution with a concentration of 5 mg / mL, and then ultrasonically mixed with the LEG suspension for 3 hours; In step (3), the added LEG / Ti3C2MXene nanomaterials can cover the surface of the working electrode ITO, and the volume can be 80 μL; In step (4), the concentration of the added aflatoxin B1 aptamer Fc-aptamer is 0.5-6 μM, the volume is 20 μL, and the incubation time is 90±2 minutes; In step (5), the mass concentration of bovine serum albumin (BSA) added dropwise is 1% and the volume is 10 μL; it is dried at room temperature for 1 hour; In step (6), the concentration of the added MB-cDNA is 1-1.5 μM, the volume is 20 μL, and the incubation time is 80±2 minutes.

[0012] Furthermore, the volume of LEG suspension and Ti3C2MXene material is 1:4-1:10.

[0013] Further, in step S21, the incubation time was 40 minutes, and after incubation, the sample was dried at room temperature and rinsed with deionized water, and then the LEG / Ti3C2-based aptamer sensor was placed in a 1 mM potassium ferrocyanide solution for differential pulse voltammetry detection.

[0014] Furthermore, the concentration of AFB1 standard solution was 1×10 -4 ng / mL-100ng / mL; During the experiment, the cyclic voltammetry (CV) voltage was set to -0.6-1V, and the differential pulse voltammetry (DPV) voltage was set to -0.5-0.6V.

[0015] Compared with the prior art, the method of detecting AFB1 using the LEG / titanium carbide-based aptasensor of the present invention has the following advantages: (1) The method for detecting AFB1 by the LEG / titanium carbide-based aptamer sensor of the present invention is to construct a sensitive interface of AFB1 on ITO with LEG / Ti3C2MXene nanomaterials, Fc-aptamer, BSA and MB-cDNA functionalized by self-assembly after ultrasonic mixing, and then drip AFB1 standard solution to form a test substrate. The test substrate is placed in the test system, and under the action of an external bias voltage, the specific binding of the aptamer on the test substrate and the target leads to a change in the electron transfer rate of the sensitive interface, causing the DPV curve to produce a corresponding current offset. The offset shows a good linear relationship with the target concentration in the range of 0.0001-100 ng / mL, thereby realizing the detection of AFB1.

[0016] (2) In the preparation of LEG / Ti3C2-based aptamer sensors, the present invention first prepares LEG suspension and Ti3C2MXene materials. LEG has excellent conductive properties, good chemical stability, and is not easy to oxidize. Ti3C2MXene has excellent conductivity and a large specific surface area, which increases the loading amount of the aptamer. Then the two are mixed to construct a sensitive interface. The high specificity and selectivity of the aptamer and the excellent conductivity of LEG and Ti3C2MXene nanomaterials are utilized to generate a corresponding current offset through the DPV curve to achieve the purpose of target detection. Among them, the construction of the sensitive interface is an essential key step in the detection of the target in the subsequent steps, and the working curve provides a calculation basis for the determination of the target concentration in the actual sample. Each step supports each other and is indispensable.

[0017] (3) The LEG / Ti3C2-based aptamer sensor prepared in the present invention combines the high conductivity of LEG and Ti3C2MXene with the specific molecular recognition of the aptamer, thereby improving the specificity of the sensor and lowering the detection line of the sensor, with the lowest detection line reaching 0.041 pg / mL.

[0018] (4) The current methods for detecting aflatoxin B1 residues in peanuts and corns are bulky and complex to operate, making it difficult to achieve timely on-site detection. However, the LEG / Ti3C2MXene-based aptamer sensor prepared in the present invention has a simple structure, high stability, excellent specificity and high sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 This is a principle block diagram of the LEG / titanium carbide-based aptasensor for detecting AFB1 according to the present invention; Figure 2 SEM images of Ti3C2Mxene material, LEG and LEG / Ti3C2Mxene nanomaterial; A is Ti3C2Mxene material, B is LEG, and C is LEG / Ti3C2Mxene nanomaterial; Figure 3 TEM images of Ti3C2Mxene material, LEG and LEG / Ti3C2Mxene nanomaterial; A is Ti3C2Mxene material, B is LEG, and C is LEG / Ti3C2Mxene nanomaterial; Figure 4 Working curve of LEG / Ti3C2-based aptasensor for detecting AFB1; Figure 5This is a graph showing the current changes as the addition ratio of LEG suspension and Ti3C2MXene material changes. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1 Preparation of LEG / Ti3C2 (titanium carbide) based aptasensor The preparation of LEG / Ti3C2-based aptasensor includes the following steps: 1. Preparation of LEG suspension (1) Weigh 0.5 g of graphite powder and disperse it in a co-solvent of 35 mL of N,N-dimethylformamide (DMF) and 15 mL of deionized water (DIW); (2) Ultrasonic treatment at 40°C for 48 hours to achieve deep stratification of graphite flakes; (3) The dispersion was centrifuged at 4000 rpm for 40 min to remove unexfoliated graphite, and two-thirds of the supernatant was collected as the LEG suspension.

[0023] Figure 2 B and Figure 3 B shows the thin and small lamellae structure of LEG.

[0024] 2. Preparation of Ti3C2MXene materials (1) Weigh 2 g of Ti3AlC2 powder and 6.4 g of lithium fluoride and disperse them in 80 mL of 9 M hydrochloric acid. Stir at room temperature for 26 hours. Then wash the mixture with deionized water and collect the solid sample. (2) Add the solid sample to deionized water and sonicate for 6 hours; (3) Freeze drying for 24 hours to obtain the final product Ti3C2Mxene material.

[0025] Figure 2 A and Figure 3 A shows the thin layer structure of Ti3C2MXene.

[0026] 3. Preparation of LEG / Ti3C2-based aptasensors (1) First, the Ti3C2MXene material was dissolved in water to form a solution with a concentration of 5 mg / mL, and then ultrasonically mixed with the LEG suspension for 3 hours; the volume ratio of the LEG suspension to the Ti3C2MXene material was 1:4; Figure 2 C and Figure 3 C shows the uniform distribution of LEG on the thin layer structure of Ti3C2MXene. The SEM image proves the morphological structure of the nanomaterial: wrinkled state and fragmented structure, and TEM proves that the nanomaterial is indeed a single-layer structure; (2) Select ITO as the working electrode and clean it with acetone, ethanol, and deionized water in sequence to remove surface dirt; (3) Dry the clean ITO in an oven, add 80 μL of LEG / Ti3C2MXene nanomaterials on the surface so that the LEG / Ti3C2MXene nanomaterials cover the surface of the working electrode, dry at room temperature, and rinse with deionized water to obtain LEG / Ti3C2MXene / ITO; The LEG / Ti3C2MXene / ITO sensor interface prepared in this step has an electroactive specific surface area that is 3.864 times higher than that of the bare ITO sensor interface. The ECSA (electrochemically active area) of the bare ITO and LEG / Ti3C2MXene / ITO are 0.194 and 0.748, respectively. The characterization method shows that the LEG / Ti3C2MXene nanomaterial has been successfully synthesized and has excellent electrochemical properties. (4) Incubate 1 μM, 20 μL of aflatoxin B1 aptamer Fc-aptamer on LEG / Ti3C2MXene / ITO for 90 minutes, dry at room temperature, and then rinse the surface with deionized water to obtain Fc-aptamer / LEG / Ti3C2MXene / ITO; (5) 10 μL of 1% bovine serum albumin (BSA) was added to Fc-aptamer / LEG / Ti3C2MXene / ITO, dried at room temperature for 1 hour, and then rinsed with deionized water to obtain BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO; (6) 1.5 μM and 20 μL of the aptamer complementary chain MB-cDNA were added onto BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO, incubated at room temperature for 80 min and rinsed with deionized water to obtain MB-cDNA / BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO, and finally the LEG / Ti3C2-based aptamer sensor MB-cDNA / BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO corresponding to aflatoxin B1 was obtained.

[0027] Table 1 MB-cDNA and Fc-aptamer base sequences

[0028] MB-cDNA is labeled with MB at the 3' end of the base sequence of SEQ ID NO. 1; Fc-aptamer is labeled with (NH2)6 at the 5' end and Fc at the 3' end of the base sequence of SEQ ID NO. 2.

[0029] Example 2 Detection of AFB1 1. Draw the working curve of AFB1 (1) AFB1 standard solution was added to the surface of MB-cDNA / BSA / Fc-aptamer / LEG / Ti3C2MXene / ITO, incubated for 40 minutes, dried at room temperature, rinsed with deionized water, and the electrode was placed in 1 mM potassium ferrocyanide solution for differential pulse voltammetry detection; (2) According to the electrical signal I Fc and I MB The working curve is drawn based on the change ratio of

[0030] Figure 4 The results showed that the linear response range of the sensor to AFB1 was 0.0001-100 ng / mL, the detection line was 0.041 pg / mL, and the linear correlation coefficient was 0.995.

[0031] 2. Detection of AFB1 in the sample to be tested The sample to be tested is dripped onto the LEG / Ti3C2-based aptamer sensor for incubation. Under the same conditions as step S21, the current value is recorded, and the concentration of AFB1 in the sample to be tested is calculated based on the working curve obtained in step S21.

[0032] Figure 1 The principle block diagram of the LEG / Ti3C2-based aptamer sensor for detecting AFB1 described in the present invention is shown.

[0033] In order to verify the application of the prepared sensor in actual sample detection, AFB1 in corn and peanut was detected under optimal conditions by the spiked method.

[0034] 5 g peanut powder was added to a 50 mL polypropylene tube and extracted with 15 mL methanol-ultrapure water solution at a ratio of 6:4 v / v and 0.50 g NaCl. Stirred on a magnetic stirrer for 10 min, the extract was centrifuged at 8000 rpm for 10 min, and then filtered with a 0.22 μm syringe filter for further purification. The obtained solution was used as a blank, and 0.1 ng / mL, 1 ng / mL, and 10 ng / mL AFB1 solutions were added to the treated solution as analytical samples for AFB1 detection and real sample analysis.

[0035] The pretreatment process of corn samples was similar to that of peanut samples.

[0036] The actual detection results of AFB1 are recorded in Table 2.

[0037] Table 2 Detection results of AFB1 in actual peanuts and corn

[0038] As can be seen from Table 2, the recoveries of peanut and corn samples were 97% to 106% and 98% to 106%, respectively, and the relative standard deviations were between 0.284% and 0.508%. These results show that the LEG / Ti3C2-based aptamer sensor prepared by the present invention and the method for detecting AFB1 have good application prospects and practical value.

[0039] Experiment 1 Optimization of the addition ratio of LEG suspension and Ti3C2MXene material In order to confirm the optimal value of the addition ratio of LEG suspension and Ti3C2MXene material, based on the above Example 1, the volume ratios of LEG suspension and Ti3C2MXene material were set to 1:1, 1:2, 1:4, 1:8, 1:10, 2:1, 4:1, 8:1, and 10:1, respectively, and the sensitivity of the prepared sensor was tested and the cyclic voltammetry was performed. The results are as follows Figure 5 shown.

[0040] from Figure 5It can be seen that with the increase of Ti3C2MXene concentration, the current value gradually increases. When the mixing ratio of LEG suspension and Ti3C2Mxene material is 1:4, the current value reaches the maximum. When the volume of Ti3C2Mxene material is increased, the current begins to decrease again. Therefore, only when the mixing ratio of LEG suspension and Ti3C2Mxene material is 1:4, it is most conducive to improving the sensitivity of the sensor. When the volume ratio of LEG suspension and Ti3C2Mxene material is between 1:4-1:10, the sensitivity is better.

[0041] Experiment 2 Optimization of Fc-aptamer modification concentration In order to confirm the optimal value of the Fc-aptamer modification concentration, based on the above Example 1, the aptamer concentrations were set to 0.1, 0.5, 1, 2, 4, 6, and 8 μM, respectively, and other conditions remained unchanged. Cyclic voltammetry was performed, and it was found that the maximum current change was obtained at 1 μM, with the best sensitivity. When the current was 0.5-6 μM, it was above 0.5△I / mA, with better sensitivity.

[0042] Table 3 Current changes with the Fc-aptamer modification concentration

[0043] Experiment 3 Optimization of MB-cDNA modification concentration In order to confirm the optimal value of MB-cDNA modification concentration, based on the above Example 1, the complementary chain concentration was set to 0.5, 1, 1.5, 2, and 2.5 μM, and other conditions remained unchanged. Cyclic voltammetry was performed, and it was found that the maximum current change was obtained at 1.5 μM, and the sensitivity was the best. At 1-1.5 μM, the current was above 0.2△I / mA, and the sensitivity was better.

[0044] Table 4 Current changes with MB-cDNA modification concentration

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting AFB1 using a LEG / titanium carbide-based aptamer sensor, characterized in that: The method comprises the following steps: S1. Preparation of LEG / Ti3C2-based aptasensor First, LEG suspension and Ti3C2 MXene material were prepared respectively, and then LEG suspension and Ti3C2 MXene material were mixed by ultrasound to obtain LEG / Ti3C2 MXene nanomaterials, and then LEG / Ti3C2 MXene nanomaterials were modified on ITO to construct a sensitive interface of AFB1, and then Fc-aptamer, BSA, and MB-cDNA were modified layer by layer to construct a sensitive interface for detecting AFB1, and finally the LEG / Ti3C2-based aptamer sensor MB-cDNA / BSA / Fc-aptamer / LEG / Ti3C2 MXene / ITO was obtained; S2. Detection of AFB1 S21. Draw the working curve of AFB1 The AFB1 standard solution was added to the LEG / Ti3C2-based aptamer sensor for incubation, and then the sensor was subjected to differential pulse voltammetry detection. Fc and I MB The working curve is drawn based on the change ratio of S22. Detection of AFB1 in the sample to be tested The sample to be tested is dripped onto the LEG / Ti3C2-based aptamer sensor for incubation. Under the same conditions as step S21, the current value is recorded, and the concentration of AFB1 in the sample to be tested is calculated based on the working curve obtained in step S21.

2. The method for detecting AFB1 using a LEG / titanium carbide-based aptasensor according to claim 1, characterized in that: The specific method for preparing LEG suspension is: (1) dispersing graphite powder in a co-solvent of N,N-dimethylformamide and deionized water; (2) Using ultrasound to deeply delaminate graphite sheets; (3) The dispersion was centrifuged to remove unexfoliated graphite, and two-thirds of the supernatant was collected as the LEG suspension.

3. The method for detecting AFB1 using a LEG / titanium carbide-based aptasensor according to claim 2, characterized in that: In step (1), the solid-liquid ratio of graphite powder to co-solvent is 1:100 g / ml, and the volume ratio of N,N-dimethylformamide to deionized water is 7:3; In step (2), ultrasonication is performed for 48±5 hours at a temperature of 40-50°C; In step (3), the centrifugation conditions are: 4000±500 rpm, 40±5 min.

4. The method for detecting AFB1 using a LEG / titanium carbide based aptasensor according to claim 1, characterized in that: The specific method for preparing Ti3C2 MXene material is: (1) Dispersing Ti3AlC2 powder and lithium fluoride in hydrochloric acid, stirring, and then washing the mixture with deionized water to collect a solid sample; (2) Add the solid sample to deionized water for ultrasonic treatment; (3) After freeze drying, the final product Ti3C2 Mxene material is obtained.

5. The method for detecting AFB1 using a LEG / titanium carbide-based aptasensor according to claim 4, characterized in that: In step (1), the mass ratio of Ti3AlC2 powder to lithium fluoride is 1:3.2, the solid-liquid ratio of Ti3AlC2 powder to lithium fluoride to hydrochloric acid is 21:200 g / ml, the concentration of hydrochloric acid is 9 M, and stirring is performed at room temperature for 26 hours; In step (2), ultrasonic treatment is performed for 6±1 hours; In step (3), freeze-drying is performed for 24-48 hours.

6. The method for detecting AFB1 using a LEG / titanium carbide based aptasensor according to claim 1, characterized in that: The specific method for preparing LEG / Ti3C2-based aptasensor is as follows: (1) Ultrasonic mixing of the prepared LEG suspension and Ti3C2 MXene material to obtain LEG / Ti3C2 MXene nanomaterials; (2) Select ITO as the working electrode and clean it with acetone, ethanol, and deionized water in sequence to remove surface dirt; (3) Dry the clean ITO in an oven, drop LEG / Ti3C2 MXene nanomaterials on the surface, dry at room temperature, and then rinse with deionized water to obtain LEG / Ti3C2 MXene / ITO; (4) Aflatoxin B1 aptamer Fc-aptamer was added dropwise onto LEG / Ti3C2 MXene / ITO, incubated and dried at room temperature, and then the surface was rinsed with deionized water to obtain Fc-aptamer / LEG / Ti3C2 MXene / ITO; (5) bovine serum albumin (BSA) was added dropwise onto Fc-aptamer / LEG / Ti3C2 MXene / ITO, dried at room temperature, and then rinsed with deionized water to obtain BSA / Fc-aptamer / LEG / Ti3C2 MXene / ITO; (6) The aptamer complementary chain MB-cDNA was dropped onto BSA / Fc-aptamer / LEG / Ti3C2 MXene / ITO, incubated at room temperature and rinsed with deionized water to obtain MB-cDNA / BSA / Fc-aptamer / LEG / Ti3C2 MXene / ITO, and finally the LEG / Ti3C2-based aptamer sensor MB-cDNA / BSA / Fc-aptamer / LEG / Ti3C2 MXene / ITO for detecting AFB1 was obtained.

7. The method for detecting AFB1 using a LEG / titanium carbide-based aptasensor according to claim 6, characterized in that: In step (1), the Ti3C2 Mxene material is first dissolved in a solvent to form a solution with a concentration of 5 mg / mL, and then ultrasonically mixed with the LEG suspension for 3 hours; In step (3), the added LEG / Ti3C2 MXene nanomaterial covers the surface of the working electrode ITO; In step (4), the concentration of the added aflatoxin B1 aptamer Fc-aptamer is 0.5-6 μM, the volume is 20 μL, and the incubation time is 90±2 minutes; In step (5), the mass concentration of bovine serum albumin (BSA) added dropwise is 1% and the volume is 10 μL; it is dried at room temperature for 1 hour; In step (6), the concentration of the added MB-cDNA is 1-1.5 μM, the volume is 20 μL, and the incubation time is 80±2 minutes.

8. The method for detecting AFB1 according to any one of claims 1 to 7, characterized in that: The volume ratio of LEG suspension and Ti3C2 MXene material is 1:4-1:

10.

9. The method for detecting AFB1 using a LEG / titanium carbide based aptasensor according to claim 1, characterized in that: In step S21, the incubation time is 40 minutes. After incubation, the sample is dried at room temperature and rinsed with deionized water. Then, the LEG / Ti3C2-based aptamer sensor is placed in a 1 mM potassium ferrocyanide solution for differential pulse voltammetry detection.

10. The method for detecting AFB1 using a LEG / titanium carbide based aptasensor according to claim 1, characterized in that: The concentration of AFB1 standard solution is 1×10 -4 ng / mL-100ng / mL; During the experiment, the cyclic voltammetry (CV) voltage was set to -0.6-1V, and the differential pulse voltammetry (DPV) voltage was set to -0.5-0.6V.

Images