Transgenic component detection method and electrochemical sensor used by same

Abstract

The invention relates to a transgenic component detection method and an electrochemical sensor used in the method, and the method comprises the following steps: adding sDNA / AuNPs (at) Cu-MOF (at) Fe3O4 into a centrifuge tube containing a hybridization buffer solution with the same amount of tDNA, incubating at 35-38 DEG C for 70-100 min, and dispersing the obtained tDNA / sDNA / AuNPs (at) Cu-MOF (at) Fe3O4 in 1 mL of the hybridization buffer solution to obtain a buffer solution system; the method comprises the following steps of: soaking BSA / cDNA / rGO / Au / GCE into a buffer solution system, hybridizing by using a capture probe previously fixed on the surface of the BSA / cDNA / rGO / Au / GCE, incubating for 70-100 minutes, washing Fe3O4 (at) Cu-MOF (at) AuNPs / sDNA / tDNA / BSA / cDNA / rGO / Au / GCE by using a Tris-HCl buffer solution, and finally measuring in a 0.1 M acetic acid buffer solution through a three-electrode system by using an electrochemical workstation. The background signal of the electrochemical DNA biosensor constructed by the method is only 49% of that of AuNPs (at) Cu-MOF.

Description

Technical Field

[0001] The present invention relates to the field of detection technology, and in particular to a method for detecting genetically modified components and an electrochemical sensor used therein. Background Art

[0002] At present, there are two main types of detection for genetically modified ingredients, namely, detection of specific protein components and specific DNA sequences in genetically modified crops. The protein test strip method using exogenous target gene expression is low-cost and easy to carry, but it only targets a certain exogenous protein, and it is necessary to eliminate various exogenous proteins one by one to achieve the purpose of detection, which is a cumbersome process. At the same time, detection through protein may easily lose activity during processing, thereby affecting the test results. As the most common nucleic acid detection method, polymerase chain reaction (PCR) has good sensitivity, but due to the complex detection process, it requires high-precision instruments, long-term operation and superb technology, and is not suitable for field applications. In addition, false positive results may occur when detecting low-concentration gene fragments.

[0003] Biosensors, including capillary biosensors, colorimetric biosensors, fluorescent biosensors and electrochemical biosensors, have become the newest and most attractive alternative platform for the detection of genetically modified organisms in food. As a mature detection technology, electrochemical sensors directly generate electrical signals through electrochemical reactions, without the need for expensive and complex signal transduction equipment. Among them, electrochemical DNA biosensors have the characteristics of simple operation, good selectivity, easy to carry, and the ability to efficiently detect DNA sequences with small sample amounts, providing a promising method for the detection of genetically modified organisms. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting genetically modified components and an electrochemical sensor used therein.

[0005] In order to achieve the above-mentioned purpose and other related purposes, the technical solution provided by the present invention is: an electrochemical sensor, the manufacturing method of which comprises: (1) Cu-MOF@Fe 3 O 4 Preparation: The ferroferric oxide magnetic nanoparticles were added to the ethanol solution of thioglycolic acid and shaken for 20-30 hours to prepare MAA-functionalized Fe 3 O 4 NPs(MAA-Fe 3 O 4 NPs); then washed with ethanol in the presence of an external magnet, and after drying, MAA-Fe 3 O 4 NPs dispersed in Cu(OAc) 2 ·H2 O in ethanol solution for 10-30 min; then 3 The BTC ethanol solution was shaken for 20-40 min, repeated 3-8 times, and the obtained material was washed with water and ethanol respectively, and then dried to obtain Cu-MOF@Fe 3 O 4 ; (2) AuNPs@Cu-MOF@Fe 3 O 4 Preparation Cu-MOF@Fe 3 O 4 Place in a centrifuge tube, add gold nanoparticle solution, shake in the dark at 1-6°C for 10-15h; after the reaction, separate with an external magnetic field and dry with ultrapure water to obtain AuNPs@Cu-MOF@Fe 3 O 4 ; (3) sDNA functionalized AuNPs@Cu-MOF@Fe 3 O 4 Preparation of signal probe AuNPs@Cu-MOF@Fe 3 O 4 Disperse in the previously prepared DNA fixation buffer solution, add sDNA, and shake overnight at 1-6°C; after the reaction, centrifuge to remove excess sDNA, wash with DNA storage buffer; finally disperse in DNA storage buffer and store at 1-6°C to obtain sDNA / AuNPs@Cu-MOF@Fe 3 O 4 .

[0006] The preferred technical solution is: Fe 3 O 4 The ratio of NPs to ethanol solution of thioglycolic acid was 0.04-0.06 g:10 mL, and the concentration of ethanol solution of thioglycolic acid was 0.29 mM; MAA-Fe 3 O 4 NPs and Cu(OAc) 2 ·H 2 The ratio of H O to ethanol solution is 0.04-0.06 g: 4 mL, and the concentration of thioglycolic acid to ethanol solution is 10 mM; 3 The concentration of BTC in ethanol solution is 10 mM and the volume is 3-6 mL.

[0007] The preferred technical solution is: Cu-MOF@Fe 3 O 4The ratio of NPs to AuNPs solution is 0.04-0.06 g: 5 mL; the preparation method of AuNPs solution includes: 4 The solution is heated to boiling, and then sodium citrate is added and heated continuously to obtain a wine-red solution. After the reaction is completed, the obtained wine-red solution is placed in the air to cool to room temperature, and then refrigerated and protected from light to obtain an AuNPs solution.

[0008] The preferred technical solution is: AuNPs@Cu-MOF@Fe 3 O 4 The ratio of DNA fixation buffer solution is 8-12 mg:1 mL; the concentration of sDNA is 10 μM, the volume is 80-120 μL; the centrifugal speed is 8000-10000 rpm, and the time is 3-8 min.

[0009] To achieve the above-mentioned purpose and other related purposes, the technical solution provided by the present invention is: a method for detecting genetically modified ingredients, comprising the following steps: 3 O 4 Add the hybridization buffer containing an equal amount of tDNA into a centrifuge tube and incubate at 35-38°C for 70-100 min. 3 O 4 Dispersed in 1 mL hybridization buffer to obtain a buffer system; BSA / cDNA / rGO / Au / GCE was immersed in the buffer system to hybridize using the capture probe previously fixed on the surface of BSA / cDNA / rGO / Au / GCE, and after incubation for 70-100 min, Fe was washed with Tris-HCl buffer. 3 O 4 @Cu-MOF@AuNPs / sDNA / tDNA / BSA / cDNA / rGO / Au / GCE, and finally measured using an electrochemical workstation in a three-electrode system in 0.1 M acetate buffer.

[0010] The preferred technical solution is: The preparation method of BSA / cDNA / rGO / Au / GCE comprises: firstly, dropping a dispersed reduced graphene oxide solution on the surface of a glassy carbon electrode, and obtaining rGO / GCE after drying; then, 4In the solution, at a constant potential of -0.2 V, electrodeposition was performed on rGO / GCE by the amperometric method to form rGO / Au / GCE; then cDNA was fixed to the surface of rGO / Au / GCE and treated at 1-6 ℃ for 8-20 h, and the unfixed cDNA was washed off to obtain cDNA / rGO / Au / GCE; bovine serum albumin solution was dropped onto cDNA / rGO / Au / GCE to treat non-specific sites, and BSA / cDNA / rGO / Au / GCE was obtained after elution.

[0011] The preferred technical solution is: polishing the glassy carbon electrode with 0.3 μm and 0.05 μm alumina powder respectively, then ultrasonicating in ultrapure water and ethanol, and finally drying with nitrogen.

[0012] The preferred technical solution is: when performing electrochemical measurement: use 0.1M acetate buffer solution as the detection base solution; use the electrochemical biosensor and then use differential pulse voltammetry as the electrochemical detection method; the measurement potential range of differential pulse voltammetry is -0.6 to 0.5V, and the scan rate is 100 mV s-1.

[0013] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: In one aspect of the present invention, the synthesis of Fe 3 O 4 , Cu-MOF@Fe 3 O 4 , AuNPs@Cu-MOF@Fe 3 O 4 After comparison, AuNPs@Cu-MOF@Fe 3 O 4 It has higher conductivity and better stability. On the other hand, an electrochemical DNA biosensor was constructed and a new core-shell magnetic MOF material (AuNPs@Cu-MOF@Fe 3 O 4 ) as signal tags, the background signal of the constructed sensor was only 49% of that of AuNPs@Cu-MOF. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Attached Figure 1 This is an electron microscope image of the nanomaterial.

[0015] Attached Figure 2 Feasibility analysis of electrochemical sensors.

[0016] Attached Figure 3 To optimize the experimental conditions.

[0017] Attached Figure 4Analytical performance of electrochemical sensors.

[0018] Attached Figure 5 For the selectivity, stability and repeatability of electrochemical sensors.

[0019] Attached Figure 6 For the detection of actual samples of electrochemical sensors.

[0020] Attached Figure 7 This is a flow chart of the production of the electrochemical sensor of the present invention. DETAILED DESCRIPTION

[0021] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0022] See also Figure 1-7 . It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0023] Unless otherwise specified, the reagents or materials described in the following examples are commercially available.

[0024] Reagents and materials: Cupric acetate monohydrate (Cu(OAc) 2 ·H 2 O), chloroauric acid (HAuCl 4 ), Sodium citrate (C 6 H 7 NaO 7 ), sodium acetate (C 2 H 3 NaO 2 ), magnesium chloride (MgCl 2 ), sodium chloride (NaCl), ethylenediaminetetraacetic acid (EDTA), potassium ferrocyanide (K 4 [Fe[Fe(CN) 6 ]), potassium ferrocyanide (K 3 [Fe(CN) 6]), potassium chloride (KCl), potassium nitrate (KNO 3 ), ethanol, acetic acid, and hydrochloric acid were purchased from Sinopharm Shanghai Chemical Reagent Co., Ltd. (Shanghai, China). 3 O 4 ) was purchased from Shanghai Chaowei Nanotechnology Co., Ltd. Tris (hydroxymethylaminomethane) (Tris) was purchased from Beijing Solebow Technology Co., Ltd. (Beijing, China). Trimesic acid (TMA), bovine serum albumin (BSA), tris(2-carboxyethyl)phosphine (TCEP), and thioglycolic acid were purchased from Aladdin Reagent Co., Ltd. (Shanghai, China). Graphene (GO) was purchased from Xianfeng Nanomaterials Technology Co., Ltd. (Jiangsu, China).

[0025] The DNA sequences used in the experiment were synthesized and purified by Sangon Biotech (Shanghai) Co., Ltd. The sequences (5'-3') are: cDNA: HS-CTG AAG GCG GG.

[0026] tDNA:ATT GTC GTT TCC CGC CTT CAG.

[0027] sDNA:AAA CGA CAA T-SH.

[0028] 1MT:ATT GTC GTT TCA CGC CTT CAG.

[0029] 2MT: ATC GTC GTT TCA CGC CTT CAG.

[0030] 3MT: ATC GTC GTT TCA CGC CTT AAG.

[0031] NC: GCT TCA TCC CAA TAT ACC TGA.

[0032] Primer F: TCC CGC TCT AGC GCT TCA AT.

[0033] Primer R: TCG AGC AGG ACC TGC AGA A.

[0034] Example 1: A method for simultaneously determining the contents of four B components and related substances in polymyxin B sulfate raw materials and preparations thereof 1. Synthetic materials include the following four parts: (1) Preparation of AuNPs 100 mL of 0.01% HAuCl 4The solution was heated to complete boiling, and then 3.5 mL of sodium citrate (1%) was quickly added and heated for 20 min to obtain a wine red solution. After the reaction was completed, the obtained wine red solution was placed in the air to cool to room temperature and stored in a refrigerator away from light.

[0035] (2) Cu-MOF@Fe 3 O 4 Preparation The purchased 0.05 g of Fe 3 O 4 NPs(Fe 3 O 4 NPs) were added to 10 mL of thioglycolic acid (MAA) (0.29 mM) ethanol solution and shaken for 24 h to prepare MAA-functionalized Fe 3 O 4 NPs. Then they were washed three times with ethanol under an external magnetic field and dried at 60 °C. 3 O 4 NPs dispersed in 4 mL of Cu(OAc) 2 · The 10 mM H2O solution was shaken thoroughly for 15 min; then 3 The ethanol solution of BTC (10 mM) was fully shaken for 30 min and repeated 5 times. During each step, it was washed with ethanol under the action of a magnetic field. Finally, the obtained material was washed three times with water and ethanol respectively and dried at 60 °C.

[0036] (3) AuNPs@Cu-MOF@Fe 3 O 4 Preparation 0.05 g of Cu-MOF@Fe 3 O 4 NPs were placed in a centrifuge tube, 5 mL of gold nanoparticle (AuNPs) solution was added, and the mixture was shaken in a refrigerator at 4 °C for 12 h away from light. After the reaction, the mixture was separated by an external magnetic field and washed three times with ultrapure water, and finally dried at 60 °C to obtain AuNPs@Cu-MOF@Fe 3 O 4 .

[0037] (4) sDNA functionalized AuNPs@Cu-MOF@Fe 3 O 4 Preparation of signal probe sDNA-functionalized AuNPs@Cu-MOF@Fe was prepared by the reaction of Au and −SH. 3 O 4 (sDNA / AuNPs@Cu-MOF@Fe 3 O4 ). 10 mg AuNPs@Cu-MOF@Fe 3 O 4 Disperse in 1 mL DNA fixation buffer, add 100 µL sDNA (10 μM), and shake overnight at 4 °C; after the reaction, centrifuge at 9000 rpm for 5 min to remove excess sDNA, and wash three times with DNA storage buffer. Finally, disperse in DNA storage buffer and store at 4 °C.

[0038] 2. Preparation of Biosensors (1) Electrode pretreatment Before modifying the electrode, GCE was polished with 0.3 and 0.05 μm alumina powders, respectively, and then ultrasonicated in ultrapure water and ethanol, and finally dried with nitrogen to obtain a smooth, mirror-like electrode surface. After that, the electrode was assembled. First, 5 μL of well-dispersed rGO solution was dropped on the electrode surface and dried at room temperature for 120 min, which was recorded as rGO / GCE. Then, 3.0 mM HAuCl 4 (Contains 0.1 mM KNO 3 ) solution, and at a constant potential of -0.2V, amperometric electrodeposition was performed for 70 s to form rGO / Au / GCE. Secondly, cDNA (10 μL, 1 μM) was fixed to the surface of the electrode, placed in a 4 ℃ environment for 12 h, and the unfixed cDNA was washed away with Tris-HCl (10 mM, pH 7.4) to obtain cDNA / rGO / Au / GCE. 1% BSA solution was added dropwise to the modified electrode to treat nonspecific sites, and BSA / cDNA / rGO / Au / GCE was obtained by eluting with Tris-HCl.

[0039] (2) Electrochemical detection First, two DNA hybridization processes were performed. In the first step, sDNA / AuNPs@Cu-MOF@Fe 3 O 4 Add to hybridization buffer containing an equal amount of target and incubate at 37°C with gentle shaking for 90 min. 3 O 4 NPs@Cu-MOF@Au were dispersed in 1 mL of hybridization buffer. Finally, BSA / cDNA / rGO / Au / GCE was immersed in the buffer to perform a second hybridization step using the capture probe previously immobilized on the electrode surface. After incubation for 90 min, the electrode was washed with Tris-HCl buffer and finally measured in 0.1 M acetate buffer.

[0040] 1. Characterization of material morphology: Scanning electron microscopy (SEM) was used to characterize the morphology and size of the prepared nanocomposites. Figure 1 As shown in A, pure Fe 3 O 4 The Cu-MOF is loaded on the Fe 3 O 4 When the outer layer is formed, it becomes a tetrahedral structure, and the diameter becomes larger. ( Figure 1 B). When AuNPs and Cu-MOF@Fe 3 O 4 After the combination, it can be clearly observed that there is no obvious change in shape, while Cu-MOF@Fe 3 O 4 The surface is covered with some tiny particles ( Figure 1 C), indicating that AuNPs were successfully deposited on the Cu-MOF@Fe 3 O 4 surface.

[0041] 2. Feasibility analysis: Verification of AuNPs@Cu-MOF@Fe 3 O 4 In terms of the enhancement effect on electrochemical signals, the DPV signals of the two materials in 0.1 M acetate buffer solution were compared. Figure 2 A shows that compared with Cu-MOF@Fe 3 O 4 Loaded electrode, AuNPs@Cu-MOF@Fe 3 O 4 After modification, AuNPs exhibited the highest peak current due to their good conductivity. 3 O 4 The electrochemical signal amplification strategy can improve the analytical performance of electrochemical sensors.

[0042] Explore Fe 3 O 4 Effect of NPs on reducing background signal, compared with AuNPs@Cu-MOF@Fe in 0.1 M acetate buffer solution 3 O 4 and the background signal of AuNPs@Cu-MOF. As shown in Figure 2B, the addition of Fe 3 O 4 NPs, the background signal current value of the constructed sensor was higher than that without Fe 3 O 4 The value of AuNPs@Cu-MOF was much lower than that of AuNPs@Cu-MOF.

[0043] 3. Condition optimization: In order to obtain the most sensitive analytical performance of the sensor, several key variables were optimized, including the pH of the acetate buffer solution, the hybridization time between tDNA and sDNA, the hybridization time between cDNA and tDNA, and the concentration of the signal tag. Figure 3 As shown, the optimal pH of the acetate buffer solution was 5.5, the optimal hybridization time between tDNA and sDNA was 90 min, the optimal hybridization time between cDNA and tDNA was 90 min, and the optimal concentration of the signal tag was 3 mg / mL.

[0044] 4. Analyze performance like Figure 4 As shown in A, Cu 2+ The DPV signal increases with the increase of tDNA concentration and finally reaches a plateau state. Figure 4 B shows the tDNA at 1.0×10 -14 M to 1.0×10 -8 In the range of 10 M, there is a good linear relationship between the current value and the logarithm of the tDNA concentration, and the calculated detection limit is 1.09×10 -15 M (S / N = 3).

[0045] 6. Selectivity, stability and repeatability By measuring the DPV signals of target DNA (tDNA), single-base mismatched DNA (Mis-1), double-base mismatched DNA (Mis-2), triple-base mismatched DNA (Mis-3), and non-complementary DNA (NC) Figure 5 A), the selectivity of the developed electrochemical biosensor was studied. It can be found that only the target DNA has a high current response, indicating that the sensor has good selectivity. In addition, Figure 5 As shown in B, the electrodes were stored at 4°C for 0, 3, 7, and 14 days to further determine their stability. After 14 days, the peak current remained at 83.6% of the initial response, indicating good stability. In addition, the repeatability of the biosensor was studied. Five different batches of biosensors were constructed and repeated five times under the same experimental conditions to detect genetically modified soybeans. Figure 5 The C showed that the RSD of the peak current values ​​among the five biosensors was approximately 4.29%, indicating that good reproducibility was achieved.

[0046] 7. Testing of actual samples The purchased GM soybean powder was used as a real sample to verify the performance of the sensor in the actual sample. The agarose gel electrophoresis detection of the PCR product of the GM soybean MON89788 gene is shown in Figure 6A. A fragment of about 142 bp appeared in the GM soybean sample (lane 2), while no band was observed in the non-GM sample (lane 3) and the blank control (lane 4), indicating that the PCR amplified the PCR product of the 142 bp fragment. The constructed biosensor was then applied to analyze the initial total DNA and PCR products ( Figure 6 B). It can be seen that the DPV response of the negative (non-GM) sample (curve b) showed almost no change compared to the blank (curve a) control. This indicates that there is no PCR product of the MON89788 gene fragment in the non-GM soybean sample. However, the DPV response of the initial total DNA (curve c) was higher than the blank signal, and in addition, the DPV response to the GM soybean PCR product increased significantly (curve d). These DPV responses are in good agreement with the results obtained by gel electrophoresis, indicating that the prepared GM soybean MON89788 biosensor has potential practical applications in the detection of GM foods and crops.

[0047] The above description is only used to explain the preferred embodiments of the present invention, and is not intended to limit the present invention in any form. Therefore, any modifications or changes made to the present invention under the same inventive spirit should still be included in the scope of protection intended by the present invention.

Claims

1. An electrochemical sensor, characterized in that: The production method includes: (1) Preparation of Cu-MOF@Fe3O4: The ferroferric oxide magnetic nanoparticles were added to an ethanol solution of thioglycolic acid and shaken for 20-30 hours to prepare MAA-functionalized Fe3O4NPs (MAA-Fe3O4NPs); then washed with ethanol in the presence of an external magnet, and after drying, the MAA-Fe3O4NPs were dispersed in an ethanol solution of Cu(OAc)2·H2O and shaken for 10-30 min; then shaken in an ethanol solution of H3BTC for 20-40 min, repeated 3-8 times, and finally the obtained material was washed with water and ethanol respectively, and dried to obtain Cu-MOF@Fe3O4; (2) Preparation of AuNPs@Cu-MOF@Fe3O4 Place Cu-MOF@Fe3O4 in a centrifuge tube, add gold nanoparticle solution, and shake in the dark at 1-6°C for 10-15h; after the reaction, separate with an external magnetic field and use ultrapure water, and then dry to obtain AuNPs@Cu-MOF@Fe3O4; (3) Preparation of sDNA functionalized AuNPs@Cu-MOF@Fe3O4 signal probe AuNPs@Cu-MOF@Fe3O4 was dispersed in the previously prepared DNA fixation buffer solution, sDNA was added, and the mixture was shaken overnight at 1-6°C. After the reaction, the excess sDNA was removed by centrifugation and the mixture was washed with DNA storage buffer. Finally, the mixture was dispersed in DNA storage buffer and stored at 1-6°C to obtain sDNA / AuNPs@Cu-MOF@Fe3O4.

2. The electrochemical sensor according to claim 1, characterized in that: The ratio of Fe3O4NPs to ethanol solution of thioglycolic acid is 0.04-0.06g:10 mL, and the concentration of ethanol solution of thioglycolic acid is 0.29 mM; the ratio of MAA-Fe3O4NPs to ethanol solution of Cu(OAc)2·H2O is 0.04-0.06g:4 mL, and the concentration of ethanol solution of thioglycolic acid is 10 mM; the concentration of ethanol solution of H3BTC is 10 mM, and the amount is 3-6 mL.

3. The electrochemical sensor according to claim 1, characterized in that: The ratio of Cu-MOF@Fe3O4NPs to AuNPs solution was 0.04-0.06g:5 mL; The preparation method of the AuNPs solution comprises: heating the HAuCl4 solution to boiling, then adding sodium citrate, and continuing heating to obtain a wine red solution; After the reaction is completed, the obtained wine red solution is placed in the air to cool to room temperature, and then refrigerated and protected from light to obtain the AuNPs solution.

4. The electrochemical sensor according to claim 1, characterized in that: The ratio of AuNPs@Cu-MOF@Fe3O4 to DNA fixation buffer solution is 8-12 mg:1 mL; the concentration of sDNA is 10 μM, the amount is 80-120 μL; the centrifugal speed is 8000-10000 rpm, and the time is 3-8 min.

5. A method for detecting genetically modified components, characterized in that: The method comprises the following steps: adding the sDNA / AuNPs@Cu-MOF@Fe3O4 described in any one of claims 1 to 4 into a centrifuge tube containing an equal amount of tDNA in a hybridization buffer, and incubating at 35-38° C. for 70-100 minutes, and then dispersing the obtained tDNA / sDNA / AuNPs@Cu-MOF@Fe3O4 in 1 mL of hybridization buffer to obtain a buffer system; BSA / cDNA / rGO / Au / GCE was immersed in the buffer system to hybridize with the capture probe previously immobilized on the surface of BSA / cDNA / rGO / Au / GCE. After incubation for 70-100 min, Fe3O4@Cu-MOF@AuNPs / sDNA / tDNA / BSA / cDNA / rGO / Au / GCE was washed with Tris-HCl buffer and finally measured in 0.1 M acetate buffer using an electrochemical workstation under a three-electrode system.

6. The method for detecting genetically modified components according to claim 5, characterized in that: The preparation method of BSA / cDNA / rGO / Au / GCE includes: firstly, dropping a dispersed reduced graphene oxide solution on the surface of a glassy carbon electrode, and obtaining rGO / GCE after drying; then, electrodepositing on rGO / GCE by an amperometric method in a HAuCl4 solution at a constant potential of -0.2V to form rGO / Au / GCE; then, fixing cDNA to the surface of rGO / Au / GCE, treating it in an environment of 1-6°C for 8-20 h, washing away the unfixed cDNA, and obtaining cDNA / rGO / Au / GCE; dropping a bovine serum albumin solution on the cDNA / rGO / Au / GCE to treat non-specific sites, and obtaining BSA / cDNA / rGO / Au / GCE after eluting.

7. The method for detecting genetically modified components according to claim 6, characterized in that: The glassy carbon electrode was polished with 0.3 μm and 0.05 μm alumina powder, respectively, and then ultrasonicated in ultrapure water and ethanol, and finally dried with nitrogen.

8. The method for detecting genetically modified components according to claim 5, characterized in that: When performing electrochemical measurement: 0.1M acetate buffer solution is used as the detection base solution; the electrochemical biosensor described in any one of claims 1 to 4 is used, and then differential pulse voltammetry is used as the electrochemical detection method; the measurement potential range of the differential pulse voltammetry is -0.6 to 0.5V, and the scan rate is 100 mV s-1.

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