ZEN electrochemical sensor and preparation method and application thereof

Abstract

The invention provides a ZEN electrochemical sensor. The ZEN electrochemical sensor is prepared by the following method: (1) synthesizing MXene; (2) synthesis of an MXene / TpPa-1-COF composite material is carried out; (3) an MXene / TpPa-1-COF dispersion liquid is dispensed on the surface of the polished GCE, and AuNPs is deposited in a HAuCl4 solution after the MXene / TpPa-1-COF dispersion liquid is dried; (4) immersing the modified electrode into a beta-CD solution, and carrying out cyclic voltammetry scanning to fix beta-CD, so as to obtain a modified electrode containing MXene / TpPa-1-COF / Au / beta-CD; and (5) constructing the ZEN electrochemical sensor of a three-electrode system by taking a saturated calomel electrode as a reference electrode, a platinum wire electrode as a contrast electrode and MXene / TpPa-1-COF / Au / beta-CD / GCE as a working electrode. The electrochemical sensor provided by the invention can be used for detecting ZEN in grains, the linear range is 0.04-0.5 mu g / mL, the detection limit is as low as 0.01 mu g / mL, the sensitivity is high, the recovery rate reaches 96.6%-108.9%, and the electrochemical sensor has the advantages of high reproducibility, low cost, simplicity and convenience in operation and the like, and is suitable for rapidly screening ZEN in grains and feeds.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical sensing, and in particular relates to a ZEN electrochemical sensor and a preparation method and application thereof. Background Art

[0002] Zearalenone (ZEN), also known as F-2 toxin, is a nonsteroidal estrogenic mycotoxin primarily produced by Fusarium graminearum. It is commonly found in various grains, including corn, wheat, and sorghum, and their derivatives. It has also been identified as an emerging contaminant in surface water. Its toxicity manifests primarily in reproductive toxicity, hepatotoxicity, immunotoxicity, genotoxicity, and carcinogenic potential, and is therefore classified as a Group III carcinogen by the International Agency for Research on Cancer (IARC). According to GB 2761-2017, the limit for ZEN in various agricultural products is 60 μg / kg, and the EU stipulates that the ZEN content in human food must not exceed 75 μg / kg. Because ZEN is widely present in grains such as corn, wheat, and sorghum, its accumulation in the food chain poses a significant threat to human and animal health.

[0003] Commonly used methods for detecting ZEN include gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), and liquid chromatography-tandem mass spectrometry (LC-MS / MS). However, these methods suffer from drawbacks such as cumbersome sample preparation, high cost, and long analysis times, which limit their further application. As an alternative technology, electrochemical methods are one of the most effective tools for rapid detection of ZEN in cereals due to their simplicity, rapidity, low cost, high sensitivity, portability, and good specificity. However, current electrochemical methods are mostly based on biomolecular receptors (such as antigens / antibodies, aptamer sensors, etc.), which are complex and costly, and require prior adsorption of the target and long incubation times.

[0004] Therefore, establishing a rapid, sensitive and accurate method to determine ZEN is of great practical significance. Summary of the Invention

[0005] The present invention first provides a method for preparing a ZEN electrochemical sensor, comprising the following steps:

[0006] (1) Synthesis of MXene: Ti3AlC2 and lithium fluoride were dissolved in hydrochloric acid and stirred at 32-36°C for 12-36 hours. The mixed solution was then taken out and centrifuged, and the precipitate was washed several times with deionized water until the pH value of the solution reached 6. After removing the supernatant, the MXene powder was freeze-dried to obtain the MXene powder. The mass ratio of Ti3AlC2 to lithium fluoride was 1:1.

[0007] (2) Synthesis of MXene / TpPa-1-COF composite material: MXene, 2,4,6-triformylphloroglucinol Tp and p-phenylenediamine Pa-1 were added to a mixture of mesitylene, dioxane and acetic acid aqueous solution, and the mixed solution was ultrasonically treated to obtain a uniformly dispersed solution; the solution was then transferred to a polytetrafluoroethylene-lined autoclave and heated at 100-140°C for 48-96 hours; the product was collected by centrifugation and vacuum dried to obtain a brick-red MXene / TpPa-1-COF heterostructure hybrid composite material; wherein the mass ratio of MXene: (Tp + Pa-1) was 1:1-8;

[0008] (3) MXene / TpPa-1-COF dispersion droplets were applied to the polished GCE surface and then dried before deposition in 1 mmol / L HAuCl4 solution with a deposition time of 20 s to 60 s and a deposition potential of -0.3 to -0.2 V.

[0009] (4) Immersing the modified electrode in a 10 mmol / L β-CD solution, and performing cyclic voltammetry scanning to fix β-CD to obtain a modified electrode MXene / TpPa-1-COF / Au / β-CD / GCE containing MXene / TpPa-1-COF / Au / β-CD; wherein the concentration of the β-CD solution is 1-50 mmol / L;

[0010] (5) A three-electrode ZEN electrochemical sensor was constructed using a saturated calomel electrode as the reference electrode, a platinum wire electrode as the comparison electrode, and MXene / TpPa-1-COF / Au / β-CD / GCE as the working electrode.

[0011] Specifically, the present invention provides a method for preparing a ZEN electrochemical sensor, comprising the following steps:

[0012] (1) Synthesis of MXene: Ti3AlC2 (2 g) and lithium fluoride (2 g) were dissolved in hydrochloric acid (20 mL) and stirred at 35 °C for 24 h. The mixed solution was then taken out and centrifuged, and the precipitate was washed several times with deionized water until the pH value of the solution reached 6. After removing the supernatant, the MXene powder was freeze-dried.

[0013] (2) Synthesis of MXene / TpPa-1-COF composite material: MXene (22.2 mg), Tp (2,4,6-triformylphloroglucinol) (63 mg, 0.3 mmol) and p-phenylenediamine (Pa-1) (48 mg, 0.45 mmol) were added to a mixture of mesitylene (1.5 mL), dioxane (1.5 mL) and aqueous acetic acid solution (0.5 mL, 3 mol / L), and the mixed solution was ultrasonically treated to obtain a uniformly dispersed solution; the solution was then transferred to a polytetrafluoroethylene-lined autoclave and heated at 120 °C for 72 h; the product was collected by centrifugation and vacuum dried to obtain a brick-red MXene / TpPa-1-COF heterostructure hybrid composite material; wherein the mass ratio of MXene: (Tp + Pa-1) is 1:1-8, preferably 1:5;

[0014] (3) MXene / TpPa-1-COF dispersion droplets were applied to the polished GCE surface and then dried and deposited in 1 mmol / L HAuCl4 solution (0.5 mol / L H2SO4 configuration). The deposition time was 20s-60s, with 30s being optimal. The deposition potential was -0.3-0.2V, with -0.2V being optimal.

[0015] (4) The modified electrode was immersed in a 10 mmol / L mono-(6-mercapto-6-deoxy)-β-cyclodextrin (β-CD) solution, and β-CD was fixed by cyclic voltammetry scanning (-1.5 V to 1.5 V, 5 cycles) to obtain a modified electrode containing MXene / TpPa-1-COF / Au / β-CD (MXene / TpPa-1-COF / Au / β-CD / GCE); wherein the concentration of the β-CD solution was 1-50 mmol / L, with 10 mmol / L being the optimal value;

[0016] (5) A three-electrode ZEN electrochemical sensor was constructed using a saturated calomel electrode as the reference electrode, a platinum wire electrode as the comparison electrode, and MXene / TpPa-1-COF / Au / β-CD / GCE as the working electrode.

[0017] The present invention also provides a ZEN electrochemical sensor prepared by the above method.

[0018] The present invention also provides an application of the above-mentioned ZEN electrochemical sensor, which can be used for detecting ZEN in cereals;

[0019] The specific detection method includes the following steps:

[0020] The cereal samples to be tested were extracted with acetonitrile / water (84:16, v / v), and the oxidation peak current of ZEN was measured by square wave voltammetry (SWV) in BR buffer solution, and quantified using a standard curve;

[0021] The specific steps of extracting the grains to be tested are as follows: the grain samples to be tested are placed in acetonitrile / water (84:16, v / v), the mixture is sonicated for 30 minutes, the supernatant is collected, centrifuged at 8000 rpm, dried with nitrogen, and then dissolved in acetonitrile for analysis;

[0022] The concentration of the BR buffer solution is 10 mmol / L and the pH value is 5.0.

[0023] The ZEN electrochemical sensor provided by the present invention has the following beneficial effects when used for ZEN detection:

[0024] High sensitivity: The MXene / COF heterostructure provides a large specific surface area and conductive channels, AuNPs catalyze the oxidation reaction, and β-CD host-guest recognition enhances selectivity, with a detection limit as low as 0.01 μg / mL;

[0025] High reproducibility: The covalent bonding of COF and MXene inhibits interlayer stacking, and β-CD is stably fixed via Au-S bonds, resulting in a signal deviation of <10% between different sensors.

[0026] Fast and efficient: No biomolecular labeling is required, detection time is less than 30 minutes, and it is suitable for on-site screening.

[0027] The ZEN electrochemical sensor provided by the present invention utilizes in situ synthesis of a highly stable, highly conductive, and large-surface-area heterogeneous composite material. Furthermore, it utilizes technical means to deposit metal ions and non-biological molecules on the material's surface, thereby enhancing the material's electrochemical detection performance and specificity. To address the existing issues of ZEN detection, such as insufficient sensitivity, reliance on biomolecules, and high cost, the present invention provides a ZEN electrochemical sensor based on a MXene / COF heterogeneous composite material combined with β-cyclodextrin. This material synergy achieves signal amplification and specific recognition, thereby enabling highly sensitive and specific rapid ZEN detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The SEM morphology of MXene / TpPa-1-COF, MXene / TpPa-1-COF / Au, and MXene / TpPa-1-COF / Au / β-CD composite materials in the embodiments of the present invention is shown in FIG.

[0029] Figure 2 In the figure, a is the Fourier transform infrared spectrum of the MXene, MXene / TpPa-1-COF / Au, and MXene / TpPa-1-COF / Au / β-CD nanocomposite materials prepared in Example 1 of the present invention, and b is the XRD diffraction pattern.

[0030] Figure 3 : SWV diagram of ZEN on different electrodes in the embodiment of the present invention

[0031] Figure 4 : ZEN detection linear range (ab) and anti-interference performance. DETAILED DESCRIPTION

[0032] It should be noted that the technical details and implementation methods described in this specification are for illustrative purposes only and are intended to assist in understanding the core aspects of the present invention. Unless otherwise specified, the technical terms used are based on common definitions in the art and are consistent with conventional technical understanding.

[0033] Reagents and instruments

[0034] Titanium aluminum carbide (Ti3AlC2) (≥98 wt%), lithium fluoride (LiF), and p-phenylenediamine were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; 2,4,6-triformylphloroglucinol (Tp) was purchased from Shanghai Titan Technology Co., Ltd.; chloroauric acid tetrahydrate (HAuCl4·4H2O) was purchased from Sinopharm Chemical Reagent Co., Ltd.; mono-(6-mercapto-6-deoxy)-β-cyclodextrin (β-CD) was purchased from Shanghai Gaoxin Chemical Glass Instrument Co., Ltd.; ZEN, vomitoxin (DON), aflatoxin B1 (AFB1), fumonisin B1 (FB1), and T-2 toxin (T-2) were purchased from Sigma-Aldrich, USA. Deionized water was used in the experiments, and all reagents were of analytical grade.

[0035] Wheat and barley samples were purchased from a local market in Shanghai, ground into powder, and sealed in aluminum foil bags and stored at room temperature.

[0036] Electrochemical tests were performed using an Aptar Multi Autolab / M204 electrochemical workstation using a three-electrode system: a glassy carbon electrode (GCE, 3 mm diameter) as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl reference electrode. All tests were performed at room temperature.

[0037] The material morphology was observed using a ZEISS Oxford Xplore 30 scanning electron microscope (SEM, 15 kV); the material structure was analyzed using a ThermoNicolet iS20 Fourier transform infrared spectrometer (FTIR) and a Rigaku SmartLab SE X-ray diffractometer (XRD); and the surface chemical state was characterized using a Thermo Scientific K-Alpha X-ray photoelectron spectrometer (XPS).

[0038] Example 1: Preparation of ZEN electrochemical sensor

[0039] (1) Synthesis of MXene: MXene was synthesized by acid etching the aluminum layer in MAX (Ti3AlC2). First, Ti3AlC2 (2 g) and lithium fluoride (2 g) were dissolved in 20 ml of hydrochloric acid and stirred at 35 °C for 24 h. The mixed solution was then taken out, washed several times with deionized water, and then centrifuged until the pH value of the solution reached 6. After removing the supernatant, the wet solid was dispersed in deionized water, ultrasonicated for 15 min, and freeze-dried to obtain MXene powder;

[0040] (2) Synthesis of MXene / TpPa-1-COF composite material: MXene (22.2 mg), Tp (63 mg, 0.3 mmol) and p-phenylenediamine (Pa-1) (48 mg, 0.45 mmol) were added to a mixture of mesitylene (1.5 mL), dioxane (1.5 mL) and aqueous acetic acid solution (0.5 mL, 3 mol / L), and the mixed solution was ultrasonically treated and stirred for 20 minutes to obtain a uniformly dispersed solution; the solution was then transferred to a polytetrafluoroethylene-lined autoclave and heated at 120 °C for 72 hours; the product was collected by centrifugation and washed three times with tetrahydrofuran and acetone respectively; the obtained precipitate was then vacuum dried at 50 °C for 6 hours. The final product was a brick-red MXene / TpPa-1-COF heterostructure hybrid composite material;

[0041] (3) The MXene / TpPa-1-COF composite material was dispersed in water to form a 1 mg / mL dispersion. 5 μL of the MXene / TpPa-1-COF dispersion was dropwise applied to the polished GCE surface. After drying, AuNPs were deposited in a 1 mmol / L HAuCl4 solution (prepared with 0.5 mol / L H2SO4) at -0.2 V for 30 s.

[0042] (4) The modified electrode was immersed in a 10 mmol / L β-CD solution and cyclic voltammetry was performed (-1.5 V to 1.5 V, 5 cycles) to fix β-CD to obtain a modified electrode containing MXene / TpPa-1-COF / Au / β-CD;

[0043] (5) A three-electrode ZEN electrochemical sensor was constructed using a saturated calomel electrode as the reference electrode, a platinum wire electrode as the comparison electrode, and MXene / TpPa-1-COF / Au / β-CD / GCE as the working electrode.

[0044] Example 2: The composite material on the modified electrode containing MXene / TpPa-1-COF / Au / β-CD prepared in Example 1 was scraped out for characterization

[0045] (1) SEM characterization

[0046] like Figure 1 As shown in a, due to the in-situ growth of TpPa-1-COF on the MXene surface, the MXene / TpPa-1-COF composite material presents a uniformly distributed flower-like loose structure. COF and MXene form an ordered structure through self-organization and aggregation with the help of hydrogen bonds. After the deposition of gold nanoparticles, the surface of the material becomes rougher, indicating that the gold nanoparticles are dispersed on the surface of MXene / TpPa-1-COF ( Figure 1 b). SEM image of MXene / TpPa-1-COF / Au / β-CD ( Figure 1 c) shows that β-CD fills the gaps in the MXene / TpPa-1-COF / Au structure and forms a secondary network.

[0047] (2) FTIR and XRD characterization

[0048] FTIR( Figure 2 a) In the spectrum, 3445.08 cm -1 OH stretching vibration peak at 587 cm -1 The Ti-C peak at 1289.16 cm -1 and 1587.97cm -1 The CN and C=C vibration peaks at 370 nm and 370 nm, respectively, confirm the existence of MXene and β-ketoamine-connected TpPa-1-COF framework. Figure 2 b) The results show that the composite material retains the characteristic peaks of MXene (002), (104), (105) crystal planes (8.8°, 39.08°, 41.8°) and TpPa-1-COF (100) crystal plane peak (4.7°), and after the introduction of gold nanoparticles (Au NPs) and β-cyclodextrin (β-CD), the material still maintains the original crystal structure, with only the (111) and (200) crystal plane peaks (38.25°, 51.8°) of Au added, indicating that the modification process did not destroy the substrate skeleton. (3) Electrochemical behavior of ZEN on different electrodes

[0049] Compared with the blank electrode, the current response increased significantly after the MXene / TpPa-1-COF was modified with Au, indicating that the hybrid composite material promoted charge transfer and enhanced conductivity due to its large specific surface area. After modification with β-CD, the oxidation peak current of ZEN increased significantly due to hydrogen bonding, which enabled β-CD to form an inclusion complex with ZEN, thus providing optimal conditions for the adsorption of ZEN. Figure 3 )

[0050] Example 3: ZEN detection

[0051] The zearalenone electrochemical sensor based on the MXene / TpPa-1-COF / Au / β-CD composite material prepared in Example 1 was applied to the direct real-time detection of zearalenone in the solution. The detection steps were as follows:

[0052] (1) The constructed electrochemical sensor was placed in 10 mmol / L Britton-Robison buffer (BR buffer solution) with a pH of 5.0;

[0053] (2) Adding the solution containing the ZEN standard to be tested to the base solution;

[0054] (3) The oxidation peak current value ip of zearalenone was determined by the SWV method, and the specific parameters were set as: potential range -0.8~1.2V, amplitude 25mV.

[0055] Observe and record the IP value near 0.88V on the curve. The linear range is from 0.04μg / mL to 0.5μg / mL. The linear regression equation is I=3.18936C-0.0065 within the concentration range, with a correlation coefficient of 0.9963 and a detection limit of 0.01μg / mL, indicating that the electrochemical sensor prepared in Example 1 has high sensitivity. Figure 4 a)

[0056] To evaluate the selectivity of the MXene / TpPa-1-COF / Au / β-CD sensor, the potential interference of other mycotoxins (AFB1, DON, FB1, T-2) that are commonly present in cereals was tested. Figure 4 As shown in b, the current changes caused by the introduction of interfering substances are all less than 10%, confirming that the sensor has excellent specificity for the target toxin.

[0057] Reproducibility: Multiple sensors were fabricated using different glassy carbon electrodes as in Example 1. The signal deviation between the electrodes was less than 10%, indicating good reproducibility. This indicates that the resulting sensors exhibited excellent anti-interference capabilities against ZEN.

[0058] Example 4: Actual sample detection

[0059] The same detection method as in Example 3 was used to detect the cereal sample solution to be analyzed.

[0060] Prior to analysis, these samples were pretreated as follows: Wheat and barley seed samples (2.0 g each) were accurately weighed and immersed in 10 mL of acetonitrile / water (84:16, v:v). The mixture was shaken for 30 minutes and then sonicated for 30 minutes. The supernatant (5 mL) was collected, centrifuged at 8000 rpm for 10 minutes, dried under nitrogen, and redissolved in acetonitrile (1 mL) for analysis.

[0061] The SWV method was used to determine the oxidation peak current (ip) of zearalenone. The ip value near 0.88 V on the curve was observed and recorded. The ip value was then substituted into the linear regression equation to calculate the ZEN content in the test solution. The results showed a recovery rate of 96.6%-108.9% for cereal samples, consistent with the UPLC-MS / MS results (RSD <15%) (Table 1), demonstrating the reliability of the method.

[0062] Table 1 Actual sample testing

[0063]

Claims

1. A method for preparing a ZEN electrochemical sensor, characterized in that The steps include: (1) Synthesis of MXene: Ti3AlC2 and lithium fluoride were dissolved in hydrochloric acid and stirred at 32-36°C for 12-36 hours. The mixed solution was then taken out and centrifuged, and the precipitate was washed several times with deionized water until the pH value of the solution reached 6. After removing the supernatant, the MXene powder was freeze-dried to obtain the MXene powder. The mass ratio of Ti3AlC2 to lithium fluoride was 1:

1. (2) Synthesis of MXene / TpPa-1-COF composite material: MXene, 2,4,6-triformylphloroglucinol Tp and p-phenylenediamine Pa-1 were added to a mixture of mesitylene, dioxane and acetic acid aqueous solution, and the mixed solution was ultrasonically treated to obtain a uniformly dispersed solution; the solution was then transferred to a polytetrafluoroethylene-lined autoclave and heated at 100-140°C for 48-96 hours; the product was collected by centrifugation and vacuum dried to obtain a brick-red MXene / TpPa-1-COF heterostructure hybrid composite material; wherein the mass ratio of MXene: (Tp + Pa-1) was 1:1-8; (3) MXene / TpPa-1-COF dispersion droplets were applied to the polished GCE surface and then dried before deposition in 1 mmol / L HAuCl4 solution with a deposition time of 20 s to 60 s and a deposition potential of -0.3 to -0.2 V. (4) Immersing the modified electrode in a 10 mmol / L β-CD solution, and performing cyclic voltammetry scanning to fix β-CD to obtain a modified electrode MXene / TpPa-1-COF / Au / β-CD / GCE containing MXene / TpPa-1-COF / Au / β-CD; wherein the concentration of the β-CD solution is 1-50 mmol / L; (5) A three-electrode ZEN electrochemical sensor was constructed using a saturated calomel electrode as the reference electrode, a platinum wire electrode as the comparison electrode, and MXene / TpPa-1-COF / Au / β-CD / GCE as the working electrode.

2. The ZEN electrochemical sensor prepared by the method of claim 1.

3. Use of the ZEN electrochemical sensor according to claim 2, which can be used for detecting ZEN in cereals.

4. Use of the ZEN electrochemical sensor according to claim 3, wherein the sensor is used for detecting ZEN in cereals, comprising the following steps: After the grain samples were extracted with acetonitrile / water, the oxidation peak current of ZEN was measured by square wave voltammetry (SWV) in BR buffer solution and quantified using a standard curve. The specific steps of extracting the grains to be tested are as follows: the grain sample to be tested is placed in acetonitrile / water, the mixture is sonicated for 30 minutes, the supernatant is collected, centrifuged at 8000 rpm, dried with nitrogen, and then dissolved in acetonitrile for analysis; wherein the volume ratio of acetonitrile / water is 84:16; The concentration of the BR buffer solution is 10 mmol / L and the pH value is 5.0.

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