Nanocomposite material, electrochemical adaptive sensor and preparation method and application thereof

Abstract

The invention relates to a nano composite material which is prepared by the following steps: mixing layered Ti3C2 and an aqueous dispersion of graphene oxide, and then adding a reducing agent and an intercalator for hydrothermal reaction to obtain a Ti3C2 / Gr material; and mixing and stirring the Ti3C2 / Gr material with a UIO-66-NH2 aqueous dispersion, carrying out centrifugal separation, adding a methylene blue aqueous solution, stirring, carrying out centrifugal separation, cleaning, and drying the precipitate to obtain the MB-coated UIO-66-NH2 / Ti3C2 / Gr nano composite material. According to the method, an MB-coated UIO-66-NH2 / Ti3C2 / Gr composite material is taken as a substrate, a carcino-embryonic antigen aptamer is fixed on the surface of a modified electrode through EDC and NHS, and non-specific adsorption sites on the modified electrode are sealed by bovine serum albumin, so that an electrochemical sensing interface for detecting carcino-embryonic antigens is constructed. The electrochemical adaptive sensor has the characteristics of strong specificity, high sensitivity, low detection limit and the like, and has important scientific significance and application value for detection of tumor markers.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nanofunctional materials and bioelectrochemical sensing, and particularly relates to a nanocomposite material, an electrochemical adaptive sensor, and a preparation method and application thereof. BACKGROUND

[0002] Carcinoembryonic antigen (CEA) is an acidic glycoprotein with human embryonic antigen characteristics. Its concentration in the serum of patients with various malignant tumors (such as colon cancer, breast cancer, lung cancer, etc.) is often significantly increased, and it is a broad-spectrum tumor marker. This index has important clinical value in the differential diagnosis, disease monitoring, and efficacy evaluation of malignant tumors. The current mainstream CEA immunoassay method has obvious shortcomings: the antibody used is unstable, high in cost and complex to prepare, and the complex serum components will interfere with the detection, which is easy to cause false positives. Therefore, it is urgent to develop a new type of sensitive and simple CEA detection technology.

[0003] Electrochemical biosensors have attracted widespread attention in the field of biomedical analysis. Unlike traditional detection methods, this technology combines low cost, portability, simple operation, rapid detection, and good reproducibility, and has high sensitivity to low-concentration tumor markers, providing a powerful analysis tool for early screening and diagnosis of cancer. Coupling electrochemical systems with nanomaterials can enhance electron transfer and interface modification, effectively improving the selectivity and stability of the sensor, and can construct a new sensing interface to achieve efficient detection of cancer markers.

[0004] Sensing materials are the key to determining the performance of electrochemical biosensors. Graphene and MXene are both considered ideal materials for constructing electrochemical biosensors due to their large specific surface area and excellent electrical conductivity. Graphene materials are prone to restacking due to strong π-π conjugation and van der Waals forces between layers, and their water solubility and electrical conductivity are affected by surface functional groups. For example, the more oxygen-containing groups, the better the water solubility, but the worse the electrical conductivity. In order to have both properties, polymers such as PVP, PEI, and PDDA are often added as protective agents. MXene materials have good hydrophilicity, but also have intrinsic defects such as accumulation and stacking due to interlayer van der Waals forces, and are easily oxidized in an oxygen-containing environment, significantly reducing their electrochemical performance. SUMMARY

[0005] The present application aims to provide a nanocomposite material, an electrochemical adaptive sensor, and a preparation method and application thereof, which realizes rapid and sensitive detection of tumor markers carcinoembryonic antigen.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is:

[0007] A method for preparing MB@UIO-66-NH2 / Ti3C2 / Gr nanocomposite material, characterized by comprising the following steps:

[0008] S1. Mix the aqueous dispersion of layered Ti3C2 and graphene oxide, then add a reducing agent and an intercalating agent to carry out a hydrothermal reaction. Separate the black product generated by the reaction by centrifugation, then wash with deionized water and dry to obtain Ti3C2 / Gr material.

[0009] S2. Mix and stir the Ti3C2 / Gr material with UIO-66-NH2 aqueous dispersion, centrifuge, add methylene blue aqueous solution and stir, centrifuge to remove unbound MB molecules, wash until the blue color of the supernatant fades, dry the dark blue precipitate to obtain MB@UIO-66-NH2 / Ti3C2 / Gr nanocomposite material.

[0010] Preferably, in step S1, the reducing agent is ascorbic acid, the intercalating agent is tetramethylammonium hydroxide solution, and the mass-volume ratio of Ti3C2, graphene oxide, ascorbic acid and tetramethylammonium hydroxide is 25mg: 25mg: 400mg~500mg: 1.2ml.

[0011] Preferably, in step S1, the hydrothermal reaction temperature is 140°C and the hydrothermal reaction time is 24 hours.

[0012] Preferably, in step S2, the mass-to-volume ratio of Ti3C2 / Gr material, UIO-66-NH2 and methylene blue aqueous solution is 1 mg: 5 mg: 1 mL.

[0013] In another aspect, the present invention provides an MB@UIO-66-NH2 / Ti3C2 / Gr nanocomposite material, which is prepared by the preparation method described above.

[0014] In another aspect, the present invention provides the application of the aforementioned nanocomposite material as a sensor in the detection of the tumor marker carcinoembryonic antigen.

[0015] In another aspect, the present invention provides a method for preparing an electrochemical aptamer sensor, comprising the following steps:

[0016] S1. The aqueous dispersion of MB@UIO-66-NH2 / Ti3C2 / Gr material is drop-coated onto the surface of a cleaned glassy carbon electrode to obtain an electrode modified with MB@UIO-66-NH2 / Ti3C2 / Gr material.

[0017] S2. The CEA aptamer was bound to the surface of the MB@UIO-66-NH2 / Ti3C2 / Gr material-modified electrode via an amide condensation reaction. Unbound aptamer molecules were washed away with deionized water, and then bovine serum albumin solution was drop-coated and allowed to react at room temperature for 1 hour to seal the non-specific binding sites on the electrode surface, thus obtaining the electrochemical aptamer sensor.

[0018] Preferably, in step S2, the CEA aptamer is bound to the surface of the MB@UIO-66-NH2 / Ti3C2 / Gr material-modified electrode via an amide condensation reaction, specifically including the following steps: EDC and NHS are dispersed in Tris-HCl buffer and mixed with an equal volume of CEA aptamer solution, then dropped onto the surface of MB@UIO-66-NH2 / Ti3C2 / Gr / GCE and incubated at room temperature.

[0019] Preferably, the mass-to-volume ratio of the EDC, NHS, and Tris-HCl buffer solution is 1 mg:1.2 mg:1 mL; and the concentration of the CEA aptamer solution is 2 μM.

[0020] In another aspect, the present invention provides the application of the electrochemical aptamer sensor prepared by the above-described preparation method in the detection of the tumor marker carcinoembryonic antigen.

[0021] Preferably, during the detection by the electrochemical aptamer sensor, CEA solutions of different concentrations are drop-coated onto the prepared aptamer-modified electrode, incubated at room temperature for 1.5 h, and the oxidation peak of methylene blue on the electrode surface is measured using the differential pulse method. The DPV oxidation peak current values ​​of CEA at different concentrations are recorded, relevant working curves are plotted, and linear fitting is performed to obtain the fitting equation.

[0022] The sample to be tested is then drop-coated onto the prepared aptamer-modified electrode, and the DPV oxidation peak current value of the electrochemical sensor is measured using the differential pulse method. Based on the fitting equation, the concentration of CEA in the sample to be tested can be calculated.

[0023] This invention utilizes Ti3C2 / Gr as a substrate to prepare a supported UIO-66-NH2 / Ti3C2 / Gr composite material. This composite material combines the high conductivity and large specific surface area of ​​two-dimensional nanomaterial graphene, the good hydrophilicity of Ti3C2 MXene, and the strong adsorption performance of small molecules by the porous structure of UIO-66-NH2MOF material. By combining these three materials, the stability of Ti3C2 is improved, avoiding the problem of reduced graphene oxide being difficult to disperse in water and thus introducing a protective agent.

[0024] This invention uses UIO-66-NH2 as a carrier to covalently couple (forming amide bonds) carcinoembryonic antigen (CEA) aptamer molecules, which are then firmly fixed to the electrode surface. Leveraging the high conductivity, large specific surface area, and strong adsorption properties of the composite material, the electrochemically active molecule methylene blue (MB) is bound to the electrode surface as a signal molecule. The difference in signal before and after the aptamer binds to the target CEA is used to detect the CEA, thereby amplifying the electrochemical signal.

[0025] This invention utilizes MB@UIO-66-NH2 / Ti3C2 / Gr composite material as a substrate. Carcinoembryonic antigen aptamer (Apt-CEA) is immobilized on the surface of a modified electrode using EDC and NHS. Non-specific adsorption sites on the modified electrode are blocked using bovine serum albumin (BSA), thus constructing an electrochemical sensing interface for detecting carcinoembryonic antigen (CEA). Using this modified electrode as the working electrode and methylene blue (MB) adsorbed on the electrode surface as the electroactive substance, the changes in MB signal at the sensing interface caused by different concentrations of CEA solution were investigated using the differential pulse method (DPV), achieving the detection of CEA. The results show that the obtained CEA electrochemical aptamer sensor exhibits excellent performance, with a linear detection range of 1.0 pg / mL to 100 ng / mL and a detection limit of 0.72 pg / mL.

[0026] This electrochemical adapter sensor is characterized by high specificity, high sensitivity, and low detection limit, and has important scientific significance and application value for the detection of tumor markers. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the fabrication process of the electrochemically adapted sensor of this invention.

[0028] Figure 2 In the image, A is the SEM image of Ti3C2, B is the SEM image of Gr, C is the SEM image of Ti3C2 / Gr, D is the SEM image of UIO-66-NH2, and E is the SEM image of UIO-66-NH2 / Ti3C2 / Gr.

[0029] Figure 3 In the image, A is the XPS plot of Ti3C2 / Gr, and B is the XPS plot of UIO-66-NH2 / Ti3C2 / Gr.

[0030] Figure 4 Electrodes with different substrate materials were tested at 5 mM [Fe(CN)6]. 3- / 4- CV test curves performed in solution;

[0031] Figure 5 DPV curves of different modified electrodes in 0.1 mM PBS (pH 7.4) buffer solution;

[0032] Figure 6 Figure A shows the DPV curves of the prepared CEA / BSA / Apt-CEA / MB@UIO-66-NH2 / Ti3C2 / Gr / GCE material at different CEA antigen concentrations (from top to bottom: 0.001 ng / mL, 0.01 ng / mL, 0.1 ng / mL, 1 ng / mL, 10 ng / mL, 100 ng / mL). Figure B shows the linear relationship between the change in DPV oxidation peak current and the logarithm of CEA concentration.

[0033] Figure 7 The prepared CEA electrochemical sensor was tested in a solution containing 0.1 ng / mL CEA and 5 ng / mL of several other interfering substances (carbohydrate antigen 125 (CA 125), human serum albumin (HSA), thrombin, lysine, and Ca). 2+ Results of selectivity testing in solution;

[0034] Figure 8 The results show the stability test results of the prepared CEA electrochemical sensor on days 1, 3, 5, and 10. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] All materials and reagents used in the following examples can be purchased from chemical reagent companies, nanomaterials companies or biopharmaceutical companies, and the experimental methods used are conventional methods unless otherwise specified.

[0037] The specific process for UIO-66-NH2 in the following examples is as follows: 81.6 mg ZrCl4 and 58 mg 2-aminoterephthalic acid were weighed and dissolved in 10 mL N,N-dimethylformamide in a 50 mL reaction vessel. 1 mL glacial acetic acid was added, and the reaction vessel was sealed and placed in an oven at 120 °C for 24 hours. The resulting white suspension was centrifuged at 7000 rpm for 5 min, and then washed twice with a mixture of DMF and methanol (volume ratio 3:1). The precipitate was dried under vacuum at 50 °C for 12 h to obtain the solid product UIO-66-NH2.

[0038] Example 1

[0039] A method for preparing MB@UIO-66-NH2 / Ti3C2 / Gr nanocomposite material includes the following steps:

[0040] (1) Mix 5 mL of 5 mg / mL multilayer Ti3C2 with 5 mL of 5 mg / mL graphene oxide (GO), add 5 mL of deionized water, then add 400 mg of ascorbic acid (AA) and 1.2 mL of 25% (wt%) tetramethylammonium hydroxide (TMAOH) solution, sonicate for 30 min, heat in a 50 mL reactor for 24 h at a temperature of 140 °C, centrifuge the black product generated by the reaction (9500 rpm, 20 min), then wash with deionized water 4 times, and freeze dry to obtain Ti3C2 / Gr composite material.

[0041] (2) Mix 10 mL of 0.5 mg / mL Ti3C2 / Gr with 10 mL of 2.5 mg / mL UIO-66-NH2, disperse by ultrasonication for 30 min, stir magnetically at room temperature for 12 h, then centrifuge, wash twice with deionized water to obtain UIO-66-NH2 / Ti3C2 / Gr composite material. Add 5 mL of 0.1 mM MB aqueous solution to the above material, stir magnetically at room temperature for 16 h, then remove unbound methylene blue molecules by centrifugation, wash 4-5 times with deionized water until the blue color of the supernatant fades, and vacuum dry the resulting dark blue precipitate for 16 h to obtain MB@UIO-66-NH2 / Ti3C2 / Gr composite material.

[0042] The nanocomposite material obtained in Example 1 is analyzed below:

[0043] The morphology of different materials was analyzed using SEM, such as Figure 2 As shown in Figure 2A, clay-like Ti3C2 prepared by LiF and HCl etching exhibits a distinct layered structure, which contrasts with the rolled-up two-dimensional nanosheet structure of graphene (Gr) prepared by redox method. Figure 2 B) Due to morphological differences, TMAOH was used as an intercalating agent to increase the specific surface area of ​​Ti3C2 MXene, disrupting or weakening the van der Waals bonds between layers. Simultaneously, ascorbic acid was used as a reducing agent to reduce the oxygen-containing groups on the graphene oxide surface, improving the material's conductivity, and slowing down the oxidation rate of Ti3C2 MXene after layering. The Ti3C2 / Gr composite nanosheets prepared by this hydrothermal reduction intercalation method (Figure 2C) have a looser structure, and thinner nanosheets can be observed. The nanosheets are well dispersed and do not easily stack, which effectively increases the specific surface area of ​​the material. Furthermore, the presence of oxygen-containing functional groups on the Ti3C2 surface provides good hydrophilicity, resulting in good water solubility of the composite material, and graphene does not require a protective agent. Figure 2 D represents UIO-66-NH2 nanoparticles synthesized via a hydrothermal method. These nanoparticles exhibit a spherical structure with a size of approximately 20 nm. From...Figure 2 As can be seen in E, UIO-66-NH2 is relatively uniformly distributed on Ti3C2 / Gr nanosheets.

[0044] The elemental composition of the prepared materials was analyzed using XPS. For example... Figure 3 As shown in Figure A, the Ti3C2 / Gr composite material contains C, Ti, O, F, and N elements simultaneously. The N element may have been introduced by the intercalating agent tetramethylammonium hydroxide. Figure 3 As shown in Figure B, the XPS analysis of the prepared ternary composite material UIO-66-NH2 / Ti3C2 / Gr detected Zr, indicating that Ti3C2 / Gr and UIO-66-NH2 successfully combined to form the UIO-66-NH2 / Ti3C2 / Gr composite material.

[0045] Comparative Example 1

[0046] (1) Mix 5 mL of 5 mg / mL multilayer Ti3C2 with 5 mL of 5 mg / mL GO, add 5 mL of deionized water, then add 400 mg of AA and 1.2 mL of 25% (wt%) TMAOH solution, sonicate for 30 min, heat in a 50 mL reactor for 24 h at a temperature of 140 °C, centrifuge the black product generated by the reaction (9500 rpm, 20 min), then wash with deionized water 4 times, and freeze dry to obtain Ti3C2 / Gr composite material.

[0047] (2) Mix 10 mL of 0.5 mg / mL Ti3C2 / Gr with 10 mL of 5 mg / mL UIO-66-NH2, disperse by ultrasonication for 30 min, stir magnetically at room temperature for 12 h, then centrifuge, wash twice with deionized water to obtain UIO-66-NH2 / Ti3C2 / Gr composite material. Add 5 mL of 0.1 mM MB aqueous solution to the above material, stir magnetically at room temperature for 16 h, then remove unbound methylene blue molecules by centrifugation, wash 4-5 times with deionized water until the blue color of the supernatant fades, and vacuum dry the resulting dark blue precipitate for 16 h to obtain MB@UIO-66-NH2 / Ti3C2 / Gr composite material.

[0048] Results show that, compared with Example 1, when Ti3C2 / Gr is combined with UIO-66-NH2, doubling the amount of UIO-66-NH2 leads to a large amount of UIO-66-NH2 agglomeration, resulting in uneven distribution of it on the two-dimensional substrate material.

[0049] Example 2

[0050] A method for preparing an electrochemical aptamer sensor includes the following steps:

[0051] (1) The glassy carbon electrode (GCE) is first polished to a mirror finish with Al2O3 powder, then ultrasonically cleaned with dilute nitric acid and deionized water respectively, and finally dried with nitrogen gas for later use.

[0052] (2) 4 μL of 2 mg / mL MB@UIO-66-NH2 / Ti3C2 / Gr slurry was drop-coated onto the surface of a cleaned glassy carbon electrode and dried at room temperature to obtain an MB@UIO-66-NH2 / Ti3C2 / Gr / GCE modified electrode;

[0053] (3) Weigh 1 mg EDC and 1.2 mg NHS and dissolve them in 1 mL Tris-HCl buffer. Mix the solution with an equal volume of 2 μM CEA aptamer (Apt-CEA) solution for 1 h to activate the carboxyl group labeled on the aptamer. Take 10 μL of the activated solution and drop it onto the surface of the MB@UIO-66-NH2 / Ti3C2 / Gr / GCE modified electrode. Incubate at room temperature for 1 h to allow the aptamer to bind to the amino group on UIO-66-NH2 through amide bonds on the electrode surface. Then rinse off the unbound aptamer molecules with deionized water to obtain Apt-CEA / MB@UIO-66-NH2 / Ti3C2 / Gr / GCE.

[0054] (4) 5 μL of bovine serum albumin (BSA) (1wt%) was drop-coated onto the surface of the above aptamer-modified electrode and allowed to act at room temperature for 1 h to block the non-specific binding sites on the electrode surface, thus obtaining BSA / Apt-CEA / MB@UIO-66-NH2 / Ti3C2 / Gr / GCE.

[0055] (5) Take 10 μL of 10 -3 ~10 3 An ng / mL CEA solution was drop-coated onto the prepared aptamer-modified electrode and incubated at room temperature for 1.5 h to obtain an electrochemical aptamer sensor CEA / BSA / Apt-CEA / MB@UIO-66-NH2 / Ti3C2 / Gr / GCE that captures the target analyte carcinoembryonic antigen.

[0056] Figure 4 [Fe(CN)6] -3 / -4 Electrochemical behavior of the solution on electrodes modified with different substrate materials. [Fe(CN)6] -3 / -4 A pair of reversible redox peaks exist on the bare glassy carbon electrode. Figure 4 (a black curve). GO, due to the large number of oxygen-containing groups on its surface, exhibits poor electrical conductivity, thus [Fe(CN)6]... -3 / -4 The redox peak current decreased significantly ( Figure 4(b. Yellow curve). When GO is reduced to Gr, the number of oxygen-containing groups on the surface decreases, the conductivity of the material increases, and the redox peak current corresponding to the modified electrode increases significantly ( Figure 4 (c Red Curve). Multilayer titanium carbide generally exhibits good conductivity; however, the introduction of functional groups such as -F, -O, and -OH during etching affects its conductivity. Therefore, although multilayer Ti3C2 shows an enhanced background current, the reversibility of the electrochemical reactions of the electroactive molecules deteriorates. Figure 4 (d blue curve). Figure 4 The green curve represents [Fe(CN)6]. -3 / -4 The CV curves on the Ti3C2 / Gr composite modified electrode show larger redox peak current values ​​and enhanced reversibility compared to graphene, indicating that [Fe(CN)6]... -3 / -4 The Ti3C2 / Gr material exhibits a relatively fast charge transfer rate on its surface. The MOF material UIO-66-NH2 has poor conductivity, leading to [Fe(CN)6]... -3 / -4 The redox peak current is much lower than that of the bare glassy carbon electrode ( Figure 4 (f-cyan curve). Therefore, the MB@UIO-66-NH2 / Ti3C2 / Gr modified electrode, due to the loading of UIO-66-NH2, [Fe(CN)6] -3 / -4 The redox peak current is smaller than that of the Ti3C2 / Gr modified electrode.

[0057] Figure 5 Electrochemical characterization curves for the CEA aptamer sensor construction process. In 0.1 mM PBS (pH 7.4) buffer, the electrochemical signal of MB on the modified electrode surface reflects the charge transfer at the electrode surface. No electrochemical signal of MB was detected on the bare GCE. Figure 5 a), while MB@UIO-66-NH2 / Ti3C2 / Gr / GCE has a distinct oxidation peak at -0.25V ( Figure 5 b). When Apt-CEA binds to the electrode surface via amide bonds, the poor conductivity of DNA molecules and the oligonucleotide chains covering the electrode surface restrict the charge transfer of MB, resulting in a decrease in its oxidation peak current. Figure 5 c); After utilizing the non-specific binding sites on the electrode surface to seal the BSA, the peak current of MB continued to decrease ( Figure 5 d). After incubating the assembled aptamer sensing electrode in CEA solution, the oxidation peak current of MB was found to be significantly reduced. Figure 5 (e) This indicates that CEA is trapped on the electrode surface, hindering charge transfer. The above test results confirm the stepwise modification process of the sensing interface of this electrochemical aptamer sensor.

[0058] The electrochemical performance of the prepared CEA electrochemical adapter sensor was tested using a three-electrode system on an electrochemical workstation. CEA / BSA / Apt-CEA / MB@UIO-66-NH2 / Ti3C2 / Gr / GCE was used as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum wire electrode as the counter electrode. All three electrodes were immersed in 0.1M pH 7.4 PBS buffer. Differential pulse voltammetry (DPV) was used to determine the oxidation peak of methylene blue on the electrode surface. The electrochemical test potential range was -0.6 to 0 V, with a potential increment of 5 mV, a pulse amplitude of 50 mV, a pulse width of 50 ms, and a pulse period of 100 ms. The DPV oxidation peak current values ​​of different CEA concentrations were recorded, relevant working curves were plotted, and linear fitting was performed to obtain the fitting equation.

[0059] When detecting CEA antigen of unknown concentration in a sample, the concentration of CEA in the sample can be obtained through the above fitting equation.

[0060] The prepared CEA electrochemical sensor was tested in a solution containing 0.1 ng / mL CEA and 5 ng / mL of several other interfering substances (HSA, CA125, Thrombin, Lysine, Ca). 2+ Selectivity tests were performed in the solution to evaluate the anti-interference performance of the electrochemical sensor. Finally, the prepared CEA electrochemical sensor was subjected to DPV tests on days 1, 3, 5, and 10 to evaluate its stability.

[0061] Figure 6 (A) DPV curves at different CEA concentrations (0.001~100 ng / mL). As can be seen from the figure, the oxidation peak current of methylene blue gradually decreases as the CEA concentration gradually increases. Figure 6 (B) is a linear relationship between the DPV oxidation peak current value and the logarithm of the CEA concentration of the prepared CEA electrochemical sensor. From the analysis, it can be found that the linear detection range of the sensor is 0.001 to 100 ng / mL and the detection limit is 0.72 pg / mL, which shows that it has good analytical performance.

[0062] Figure 7 The prepared CEA electrochemical sensor was tested in a solution containing 0.1 ng / mL CEA and 50 times the concentration of several other interfering substances (CA 125, HSA, Thrombin, Lysine, Ca). 2+ Selectivity analysis was performed. The response signal of the aptamer sensing electrode to CEA was significantly higher than that of the interfering components, indicating that the sensor prepared in this study has good anti-interference performance and will not be affected by other substances.

[0063] Figure 8The stability test results of the prepared CEA electrochemical sensor are shown on days 1, 3, 5, and 10. The response value at day 10 is 93.4% of the initial value, which proves that the sensor has good stability.

Claims

1. A method for preparing MB@UIO-66-NH2 / Ti3C2 / Gr nanocomposite, characterized in that, The method comprises the following steps: S1, mixing an aqueous dispersion of layered Ti3C2 and graphene oxide, then adding a reducing agent and an intercalation agent to perform a hydrothermal reaction to obtain a Ti3C2 / Gr material; S2, mixing and stirring the Ti3C2 / Gr material with an aqueous dispersion of UIO-66-NH2, centrifugal separation, stirring with an aqueous solution of methylene blue, centrifugal separation, washing, drying the precipitate to obtain a MB@UIO-66-NH2 / Ti3C2 / Gr nanocomposite.

2. The production method according to claim 1, characterized by, In step S1, the reducing agent is ascorbic acid, the intercalation agent is a tetramethylammonium hydroxide solution, and the mass / volume ratio of Ti3C2, graphene oxide, ascorbic acid and tetramethylammonium hydroxide is 25 mg: 25 mg: 400 mg-500 mg: 1.2 ml.

3. The preparation method according to claim 1, characterized in that, In step S1, the hydrothermal reaction temperature is 140 DEG C, and the hydrothermal reaction time is 24 h.

4. The production method according to claim 1, characterized by, In step S2, the mass / volume ratio of Ti3C2 / Gr material, UIO-66-NH2 and aqueous solution of methylene blue is 1 mg: 5 mg: 1 mL.

5. A MB@UIO-66-NH2 / Ti3C2 / Gr nanocomposite prepared by the preparation method of any one of claims 1-4.

6. The application of the nanocomposite of claim 5 as a sensor in detecting tumor marker carcinoembryonic antigen.

7. A method of preparing an electrochemical aptamer sensor, characterized by, The method comprises the following steps: S1, dropping a water dispersion of the MB@UIO-66-NH2 / Ti3C2 / Gr material on the surface of a glassy carbon electrode to obtain a MB@UIO-66-NH2 / Ti3C2 / Gr material modified electrode; S2, combining a CEA aptamer on the surface of the MB@UIO-66-NH2 / Ti3C2 / Gr material modified electrode through an amide condensation reaction, then dropping a bovine serum albumin solution to obtain an electrochemical aptamer sensor.

8. The preparation method according to claim 7, characterized in that, In step S2, the CEA aptamer is combined on the surface of the MB@UIO-66-NH2 / Ti3C2 / Gr material modified electrode through an amide condensation reaction, which specifically comprises the following steps: dispersing EDC and NHS in a Tris-HCl buffer solution, mixing with an equal volume of a CEA aptamer solution, dropping on the surface of the MB@UIO-66-NH2 / Ti3C2 / Gr / GCE, and incubating at room temperature.

9. The production method according to claim 8, characterized by, The mass / volume ratio of the EDC, NHS and Tris-HCl buffer solution is 1 mg: 1.2 mg: 1 mL; and the concentration of the CEA aptamer solution is 2 μM.

10. The application of the electrochemical aptamer sensor prepared by the preparation method of claim 7 in detecting tumor marker carcinoembryonic antigen.

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