Preparation and application of multifunctional electrochemical sensor based on biomimetic catalyst functionalized nanosheet
By combining graphene with bionic catalysts, functionalized nanosheets of bionic catalysts were prepared, which solved the shortcomings of existing electrochemical sensors in terms of diversity and selectivity detection, and achieved high sensitivity detection and stability for a variety of target objects. promote.
Patent Information
- Application Number
- CN202311055774.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-21
- Publication Date
- 2025-02-21
AI Technical Summary
The diversity and practicality of existing electrochemical sensors in detecting multiple analytes and achieving selective detection in complex systems still need to be improved, and bionic catalysts such as metal phthalocyanine and metalporphyrin are poor in conductivity and dispersion due to their poor conductivity and dispersion. , difficult to directly use in electrochemical detection.
Bionic catalyst functionalized nanosheets are prepared by combining graphene with bionic catalysts such as metalporphyrin or metal phthalocyanine, and used for the preparation of electrochemical sensors, using strong electrostatic interactions and π-π interactions. Immobilized the bionic catalyst on graphene to improve conductivity and stability.
The multifunctional and selective detection capabilities of electrochemical sensors have been improved, and the detection sensitivity and stability of target substances such as paraoxygen phosphorus, hydrogen peroxide and nitric oxide have been improved, simplified the synthesis process and reduced the cost of raw materials.
Smart Images
Figure BDA0004406001780000021 
Figure HDA0004406001790000011 
Figure HDA0004406001790000012
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electrochemical sensors, and in particular relates to the preparation and application of a multifunctional electrochemical sensor based on bionic catalyst functionalized nanosheets. Background Art
[0002] Electrochemical sensors play a key role in accurately quantifying specific analytes by monitoring the changes in the measurable electrical signal generated by the interaction between the analyte and the sensing interface. Compared with traditional analytical methods such as chromatography and mass spectrometry, electrochemical sensors provide a better alternative because they avoid complex and cumbersome sample handling, bulky and expensive instruments, and long analysis times. Electrochemical sensors have significant advantages such as fast response time, high efficiency, easy operation, and easy miniaturization. Therefore, they have attracted extensive research attention and become an indispensable tool in fields such as biochemical analysis and environmental monitoring.
[0003] The development of electrochemical sensors is inseparable from the innovation of working electrode materials. The progress of nanomaterials has significantly improved the key parameters of electrochemical sensing, especially sensitivity. Nanomaterials have high specific surface area characteristics, which can increase the enrichment of analytes on the electrode surface and accelerate the transport of analytes, thereby amplifying electrochemical signals and improving sensitivity. Although the currently reported materials perform well in the electrochemical detection performance of certain analytes, these materials also have some unfavorable characteristics, such as complex synthesis processes, expensive raw materials and limited stability, which hinder the commercialization and promotion of electrochemical sensors based on new nanomaterials. In addition, the diversity of existing electrochemical sensors in detecting multiple analytes and achieving selective detection in complex systems needs to be improved, which limits the practicality of electrochemical sensors.
[0004] Metallophthalocyanines and metalloporphyrins are a class of biomimetic small molecules whose internal structures are similar to natural biomolecules such as horseradish peroxidase, chlorophyll, hemoglobin, and vitamin B12. These biomimetic molecules have excellent chemical stability, tunable structures, extended π systems, and well-defined active centers. Therefore, they are very suitable as selective redox catalysts and electron transfer mediators for electrochemical detection of a variety of targets. However, metallophthalocyanines and metalloporphyrins have poor conductivity and dispersibility, which are not conducive to the transmission of electrical signals and the exposure of active sites, making it difficult to directly use metallophthalocyanines and metalloporphyrins as electrode materials for electrochemical detection. Summary of the invention
[0005] In view of the deficiencies of the above technologies, the purpose of the present invention is to provide the preparation and application of a multifunctional electrochemical sensor based on biomimetic catalyst functionalized nanosheets.
[0006] To achieve the above object, the present invention is implemented through the following technical solutions:
[0007] In one aspect, the present invention provides a synthesis process of biomimetic catalyst functionalized nanosheets, comprising the following steps:
[0008] Graphene was dispersed in acetonitrile and sonicated for 10–60 min to obtain 0.1–0.4 mg mL -1 Then, under stirring, a biomimetic catalyst solution (0.5-2 mg mL -1 ) is added to the graphene dispersion to obtain a mixed solution. Subsequently, 3,4-ethylenedioxythiophene and an initiator are continuously added to the mixed solution, wherein the mass ratio of 3,4-ethylenedioxythiophene to graphene is 2-10. After stirring for 12 hours, the solution is centrifuged and washed three times with ethanol and ultrapure water respectively to obtain a biomimetic catalyst functionalized nanosheet;
[0009] The bionic catalyst belongs to metal porphyrin or metal phthalocyanine, and their derivatives.
[0010] Furthermore, in the above technical solution, the graphene is ultrasonically treated in acetonitrile for 10-60 minutes.
[0011] Furthermore, in the above technical solution, the bionic catalyst includes sulfonated cobalt phthalocyanine (CoPc), heme (FePr), and tetrasulfonated nickel phthalocyanine (NiPc); the solvent in the solution of the bionic catalyst is an aqueous solution or a mixed solution of water and DMSO; the initiator includes ammonium persulfate, ferric chloride, and tetrachloroauric acid.
[0012] Bionic Catalyst
[0013]
[0014] The synthesis method of CoPc-based functionalized nanosheets is as follows: graphene is dispersed in acetonitrile and ultrasonicated for 10-60 min to obtain 0.1-0.4 mg mL -1 Then, a CoPc aqueous solution (0.5-2 mg mL -1 ) was added to the graphene dispersion to obtain a mixed solution; then, 3,4-ethylenedioxythiophene and an aqueous solution of ammonium persulfate (2-10 mg mL -1 ) is continuously added to the mixed solution, wherein the mass ratio of 3,4-ethylenedioxythiophene to graphene is 2-10, and the volume ratio of the ammonium persulfate aqueous solution to 3,4-ethylenedioxythiophene is 1-10; after stirring for 12 hours, the solution is centrifuged and washed three times with ethanol and ultrapure water respectively to obtain CoPc-based functionalized nanosheets CoPcNS;
[0015] The synthesis method of FePr-based functionalized nanosheets is as follows: graphene is dispersed in acetonitrile and ultrasonicated for 10-60 min to obtain 0.1-0.4 mg mL -1 Then, under stirring, a FePr solution (0.5-2 mg mL -1 , a mixed solvent of DMSO and ultrapure water (volume ratio 2:1-1:2) was added to the graphene dispersion to obtain a mixed solution; then, 3,4-ethylenedioxythiophene and an aqueous solution of ammonium persulfate (2-10 mg mL -1 ) are continuously added to the mixed solution, wherein the mass ratio of 3,4-ethylenedioxythiophene to graphene is 2-10, and the volume ratio of the ammonium persulfate aqueous solution to 3,4-ethylenedioxythiophene is 1-10; after stirring for 12 hours, the solution is centrifuged and washed three times with ethanol and ultrapure water respectively to obtain a functionalized nanosheet FePrNS based on FePr;
[0016] The synthesis method of NiPc-based functionalized nanosheets is as follows: graphene is dispersed in acetonitrile and sonicated for 10-60 min to obtain 0.1-0.4 mg mL -1 Then, under stirring, a NiPc solution (0.5-2 mg mL -1 ) was added to the graphene dispersion to obtain a mixed solution; then, 3,4-ethylenedioxythiophene and an aqueous solution of ammonium persulfate (2-10 mg mL -1 ) is continuously added into the mixed solution, wherein the mass ratio of 3,4-ethylenedioxythiophene to graphene is 2-10, and the volume ratio of ammonium persulfate aqueous solution to 3,4-ethylenedioxythiophene is 1-10; after stirring for 12 hours, the solution is centrifuged and washed three times with ethanol and ultrapure water respectively to obtain NiPc-based functionalized nanosheets NiPcNS.
[0017] The present invention provides an electrochemical biosensor based on biomimetic catalyst functionalized nanosheets for detecting organophosphorus pesticides.
[0018] (1) mixing the dispersion of the above-mentioned CoPc-based functionalized nanosheet CoPcNS with a model enzyme and a chitosan solution, and dripping the mixture onto the surface of a glassy carbon electrode, and allowing the mixture to stand and dry at room temperature to obtain an electrochemical biosensor for detecting organophosphorus pesticides;
[0019] (2) immersing the electrochemical biosensor in an acetylthiocholine chloride solution, performing a constant potential scan at a working potential, and recording the current intensity i1;
[0020] (3) taking out the electrochemical biosensor, washing it with a buffer solution, and then immersing it in a sample to be tested for incubation;
[0021] (4) taking out the electrochemical biosensor, washing it with a buffer solution, and then immersing it in an acetylthiocholine chloride solution of the same concentration as in step (1), and recording the current intensity i2 by constant potential scanning at the same working potential. The inhibition rate I is (i1-i2) / i1, and a correlation curve between the inhibition rate and the concentration of the organophosphorus pesticide is obtained;
[0022] (5) Calculate the content of organophosphorus pesticides in the sample to be analyzed by using the correlation curve between the inhibition rate and the concentration of the organophosphorus pesticides.
[0023] Furthermore, in the above technical solution, the preparation method of the electrochemical biosensor in step (1) is as follows: polishing the surface of the glassy carbon electrode with aluminum oxide powder, ultrasonically cleaning it in deionized water and anhydrous ethanol in turn, and drying it under nitrogen. Dissolve chitosan in 0.5-4% acetic acid to obtain 2.5-10 mg mL -1 Chitosan solution was mixed with CoPcNS (0.2-1 mg mL -1 ) and model enzyme solution (0.1-0.4UμL -1 Finally, the mixture was dripped onto a freshly cleaned glassy carbon electrode and dried at room temperature to obtain an electrochemical biosensor.
[0024] Furthermore, in the above technical scheme, the model enzyme in step (1) includes acetylcholinesterase and butyrylcholinesterase; the working potential in step (2) is 0-0.4V; the buffer solution in step (3) is a phosphate buffer, that is, a mixed aqueous solution of Na2HPO4 and NaH2PO4 with equimolar concentrations of 20-100mmol / L, and its pH is 6-8; the incubation time in step (3) is 5-20min; the samples to be tested in step (3) are fruit and vegetable samples and water samples; the organophosphorus pesticides in step (3) include paraoxon, parathion, dichlorvos, and chlorpyrifos.
[0025] The present invention provides a method for preparing the electrochemical sensor based on the biomimetic catalyst functionalized nanosheet and applying the electrochemical sensor to detect hydrogen peroxide. The preparation and application of the electrochemical sensor include the following steps:
[0026] (1) mixing the dispersion of the above-mentioned FePr-based functionalized nanosheets FePrNS with an aqueous solution of Nafion and dropping the mixture onto the surface of a glassy carbon electrode, leaving the mixture to dry at room temperature, and obtaining an electrochemical sensor for detecting hydrogen peroxide;
[0027] (2) Immersing the electrochemical sensor in a buffer solution under the protection of nitrogen, and continuously dripping a standard solution of hydrogen peroxide into the buffer solution. Performing a constant potential scan to obtain a current-time relationship curve. Based on the steady-state current corresponding to different concentrations of hydrogen peroxide, a correlation curve between current intensity and hydrogen peroxide concentration can be obtained;
[0028] (3) The content of hydrogen peroxide in the sample to be analyzed is calculated using the correlation curve between the current intensity and the hydrogen peroxide concentration.
[0029] Furthermore, in the above technical solution, in step (2), the working potential is -0.1-0.4 V; the buffer solution in step (2) is a phosphate buffer solution, i.e., a mixed aqueous solution of Na2HPO4 and NaH2PO4 with equimolar concentrations of 20-100 mmol / L, and its pH is 6-8.
[0030] The present invention provides a method for preparing the electrochemical sensor based on the biomimetic catalyst functionalized nanosheet and applying the same to detect nitric oxide, wherein the preparation and application of the electrochemical sensor comprises the following steps:
[0031] (1) mixing the dispersion of the NiPc-based functionalized nanosheet NiPcNS and the aqueous solution of Nafion, and dropping the mixture onto the surface of a glassy carbon electrode, and allowing the mixture to stand and dry at room temperature to obtain an electrochemical sensor for detecting nitric oxide;
[0032] (2) Immersing the electrochemical sensor in a buffer solution under the protection of nitrogen, and continuously dripping a standard solution of nitric oxide into the buffer solution. Performing a constant potential scan to obtain a current-time relationship curve. Based on the steady-state current corresponding to different concentrations of nitric oxide, a correlation curve between current intensity and nitric oxide concentration can be obtained;
[0033] (3) The content of nitric oxide in the sample to be analyzed is calculated by using the correlation curve between the current intensity and the nitric oxide concentration.
[0034] Furthermore, in the above technical solution, in step (1), the preparation method of the electrochemical sensor is: polishing the surface of the glassy carbon electrode with aluminum oxide powder, ultrasonically cleaning it in deionized water and anhydrous ethanol in turn, and drying it under nitrogen. -1 The FePrNS or NiPcNS suspension was dropped onto a glassy carbon electrode and dried at room temperature to obtain the FePrNS or NiPcNS-based sensors.
[0035] Furthermore, in the above technical solution, in step (2), the working potential is 0.5-1V; the buffer solution in step (2) is a phosphate buffer solution, that is, a mixed aqueous solution of Na2HPO4 and NaH2PO4 with equimolar concentrations of 20-100mmol / L, and its pH is 6-8.
[0036] The beneficial effects of the present invention are:
[0037] 1. The present invention has the characteristics of simple synthesis process, no need for harsh reaction conditions, and low raw material cost.
[0038] 2. The positively charged conductive polymer poly (3,4-ethylenedioxythiophene) can fix the negatively charged biomimetic catalyst on the conductive graphene through strong electrostatic interaction and π-π interaction, thereby achieving rapid charge transfer and significantly enhanced stability.
[0039] 3. The functionalized nanosheets have good conductivity and an open two-dimensional structure with exposed active sites, which are conducive to the superior performance of electrochemical sensing.
[0040] 4. The present invention has universal applicability. Different functionalized nanosheets can be prepared by using different biomimetic catalysts, and further specific detection of targets such as paraoxon, hydrogen peroxide and nitric oxide can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments are briefly introduced below.
[0042] Figure 1 This is the steady-state current at different paraoxon concentrations in Example 1.
[0043] Figure 2 This is a linear correlation curve between the inhibition rate and the paraoxon concentration in Example 1.
[0044] Figure 3 1 is the time-current curve under different hydrogen peroxide concentrations of Example 2.
[0045] Figure 4 This is the linear correlation curve between the current intensity and the hydrogen peroxide concentration in Example 2.
[0046] Figure 5 This is the time-current curve under different nitric oxide concentrations in Example 3.
[0047] Figure 6 This is the linear correlation curve between the current intensity and the nitric oxide concentration in Example 3. DETAILED DESCRIPTION
[0048] The following examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.
[0049] Example 1: Preparation of electrochemical sensor based on CoPc functionalized nanosheets and its application in paraoxon detection
[0050] 2 mg of graphene was dispersed in 10 mL of acetonitrile and sonicated for 30 min. Then, 5 mL of CoPc aqueous solution (1 mg mL -1 ) was added to the graphene dispersion. Subsequently, 20 μL of 3,4-ethylenedioxythiophene and 80 μL of ammonium persulfate aqueous solution (8.5 mg mL -1 ) was continuously added to the solution. After stirring for 12 hours, the solution was centrifuged and washed three times with ethanol and ultrapure water, respectively, to obtain CoPc-based nanosheets CoPcNS.
[0051] The surface of the glassy carbon electrode was polished with aluminum oxide powder, ultrasonically cleaned in deionized water and anhydrous ethanol, and dried under nitrogen. Chitosan was dissolved in 2% acetic acid to obtain 5 mg mL -1 Chitosan solution was mixed with CoPcNS (0.5 mg mL -1 ) and acetylcholinesterase solution (0.2UμL -1 , dissolved in 50 mM pH=7 phosphate buffer) and mixed thoroughly. Finally, 4 μL of the mixture was dripped onto the freshly cleaned glassy carbon electrode and dried at room temperature to obtain an electrochemical biosensor.
[0052] The three-electrode system consisting of the electrochemical biosensor was immersed in a 5mM acetylthiocholine chloride detection solution (5mL phosphate buffer), and the current-time measurement was performed at 0.1V, and the stable current i1 was recorded. After the sensor was taken out, it was rinsed with phosphate buffer and then immersed in different concentrations of paraoxon phosphate buffer for incubation for 15min. After the electrode was taken out, it was rinsed with phosphate buffer and then immersed in the same acetylthiocholine chloride phosphate buffer to measure the stable current i2. The different i2 obtained are as follows Figure 1 shown. Figure 1 The horizontal axis is the time of the current-time measurement, and the vertical axis is the current. As the concentration of paraoxon increases, the stable current i2 decreases continuously. The inhibition rate I can be expressed as (i1-i2) / i1. The relationship between the inhibition rate and the pesticide concentration is as follows: Figure 2 As shown, the linear range is 10-2000 ppb and the detection limit is 1.1 ppb.
[0053] Paraoxon was added to phosphate buffer, tap water and cucumber juice, and the inhibition rate was detected by the prepared electrochemical biosensor. Tap water and cucumber juice were first filtered through a 0.45μm filter to remove suspended matter, and then mixed with phosphate buffer in a volume ratio of 1:1. The electrochemical biosensor was used to detect phosphate buffer, tap water and cucumber juice containing 100ppb paraoxon, and the inhibition rates were 39.7%, 37.2% and 38.2%, respectively. This shows that the electrochemical biosensor can be used for the detection of actual samples with good accuracy.
[0054] Example 2: Preparation of electrochemical sensor based on FePr functionalized nanosheets and its application in hydrogen peroxide detection
[0055] 2 mg of graphene was dispersed in 10 mL of acetonitrile and sonicated for 30 min, and then 5 mL of FePr solution (1 mg mL -1 , a mixed solvent of DMSO and ultrapure water (volume ratio 2:3) was added to the graphene dispersion. Subsequently, 20 μL of 3,4-ethylenedioxythiophene and 80 μL of ammonium persulfate aqueous solution (8.5 mg mL -1 ) was continuously added to the solution. After stirring for 12 hours, the solution was centrifuged and washed three times with ethanol and ultrapure water respectively to obtain FePr-based nanosheets FePrNS.
[0056] The surface of the glassy carbon electrode was polished with aluminum oxide powder, ultrasonically cleaned in deionized water and anhydrous ethanol, and dried under nitrogen. 4 μL of 0.5 mg mL Nafion -1 The FePrNS suspension was dropped onto a glassy carbon electrode and dried at room temperature to obtain a FePrNS-based sensor.
[0057] The three-electrode system composed of the FePrNS-based sensor was immersed in 5 mL of phosphate buffer under the protection of nitrogen, and the standard solution of hydrogen peroxide was continuously added to the phosphate buffer. A constant potential scan was performed at -0.2 V to obtain the current-time relationship curve, as shown in FIG. Figure 3 shown. Figure 3 The horizontal axis is the time of the current-time measurement, and the vertical axis is the current. As hydrogen peroxide is continuously added, the current signal gradually increases. According to the steady-state current corresponding to different concentrations of hydrogen peroxide, the correlation curve between current intensity and hydrogen peroxide concentration can be obtained, such as Figure 4 As shown, the linear ranges were 10-110 μM and 110-430 μM, respectively, and the detection limit was 4.9 μM.
[0058] Example 3: Preparation of electrochemical sensor based on NiPc functionalized nanosheets and its application in nitric oxide detection
[0059] 2 mg of graphene was dispersed in 10 mL of acetonitrile and sonicated for 30 min. Then, 5 mL of NiPc aqueous solution (1 mg mL -1 ) was added to the graphene dispersion. Subsequently, 20 μL of 3,4-ethylenedioxythiophene and 80 μL of ammonium persulfate aqueous solution (8.5 mg mL -1 ) was continuously added to the solution. After stirring for 12 hours, the solution was centrifuged and washed three times with ethanol and ultrapure water, respectively, to obtain NiPc-based nanosheets NiPcNS.
[0060] The surface of the glassy carbon electrode was polished with aluminum oxide powder, ultrasonically cleaned in deionized water and anhydrous ethanol, and dried under nitrogen. 4 μL of 0.5 mg mL Nafion -1 The NiPcNS suspension was dropped onto a glassy carbon electrode and dried at room temperature to obtain a NiPcNS-based sensor.
[0061] The three-electrode system composed of the NiPcNS-based sensor was immersed in 5 mL of phosphate buffer under the protection of nitrogen, and the standard solution of nitric oxide was continuously added to the phosphate buffer. A constant potential scan was performed at 0.8 V to obtain the current-time relationship curve, as shown in FIG. Figure 5 shown. Figure 5 The horizontal axis is the time of the current-time measurement, and the vertical axis is the current. As nitric oxide is continuously added, the current signal gradually increases. According to the steady-state current corresponding to different concentrations of nitric oxide, the correlation curve between current intensity and nitric oxide concentration can be obtained, such as Figure 6 As shown, the two linear ranges were 3.6-163.8 μM and 163.8-379.8 μM, respectively, and the detection limit was 2.9 μM.
[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for synthesizing biomimetic catalyst functionalized nanosheets, characterized in that: Graphene was dispersed in acetonitrile and sonicated to obtain 0.1-0.4 mg mL -1 Then, 0.5-2 mg mL of graphene dispersion was added with stirring at a volume ratio of 1:1-1:4 to the graphene dispersion. -1 The biomimetic catalyst solution is added to the graphene dispersion to obtain a mixed solution; subsequently, 3,4-ethylenedioxythiophene and an initiator are continuously added to the mixed solution, wherein the mass ratio of 3,4-ethylenedioxythiophene to graphene is 2-10; after stirring, the solution is centrifuged, and washed three times with ethanol and ultrapure water respectively to obtain biomimetic catalyst functionalized nanosheets; The bionic catalyst belongs to metal porphyrin or metal phthalocyanine, and their derivatives.
2. The synthesis method according to claim 1, characterized in that: The biomimetic catalyst includes sulfonated cobalt phthalocyanine (CoPc), heme (FePr), and tetrasulfonated nickel phthalocyanine (NiPc); the solvent in the solution of the biomimetic catalyst is an aqueous solution or a mixed solution of water and DMSO; the initiator includes ammonium persulfate, ferric chloride, and tetrachloroauric acid; The synthesis method of CoPc-based functionalized nanosheets is as follows: graphene is dispersed in acetonitrile and sonicated to obtain 0.1-0.4 mg mL -1 Then, 0.5-2 mg mL of graphene dispersion was added with stirring at a volume ratio of 1:1-1:4 to the graphene dispersion. -1 The CoPc aqueous solution was added to the graphene dispersion to obtain a mixed solution; then, 3,4-ethylenedioxythiophene and 2-10 mg mL -1 The ammonium persulfate aqueous solution is continuously added to the mixed solution, wherein the mass ratio of 3,4-ethylenedioxythiophene to graphene is 2-10, and the volume ratio of the ammonium persulfate aqueous solution to 3,4-ethylenedioxythiophene is 1-10; after stirring, the solution is centrifuged, and washed with ethanol and ultrapure water, respectively, to obtain CoPc-based functionalized nanosheets CoPcNS; The synthesis method of FePr-based functionalized nanosheets is as follows: graphene is dispersed in acetonitrile and ultrasonicated to obtain 0.1-0.4 mg mL -1 Then, 0.5-2 mg mL of graphene dispersion was added with stirring at a volume ratio of 1:1-1:4 to the graphene dispersion. -1 The FePr solution (the solvent is a mixed solvent of DMSO and ultrapure water in a volume ratio of 2:1-1:2) is added to the graphene dispersion to obtain a mixed solution; then, 3,4-ethylenedioxythiophene and 2-10 mg mL -1 An ammonium persulfate aqueous solution (continuously added to the mixed solution, wherein the mass ratio of 3,4-ethylenedioxythiophene to graphene is 2-10, and the volume ratio of the ammonium persulfate aqueous solution to 3,4-ethylenedioxythiophene is 1-10; after stirring, the solution is centrifuged, and washed with ethanol and ultrapure water respectively to obtain a functionalized nanosheet FePrNS based on FePr; The synthesis method of NiPc-based functionalized nanosheets is as follows: graphene is dispersed in acetonitrile and sonicated to obtain 0.1-0.4 mg mL -1 Then, 0.5-2 mg mL of graphene dispersion was added with stirring at a volume ratio of 1:1-1:4 to the graphene dispersion. -1 The NiPc solution was added to the graphene dispersion to obtain a mixed solution; then, 3,4-ethylenedioxythiophene and 2-10 mg mL -1 An ammonium persulfate aqueous solution is continuously added to the mixed solution, wherein the mass ratio of 3,4-ethylenedioxythiophene to graphene is 2-10, and the volume ratio of the ammonium persulfate aqueous solution to 3,4-ethylenedioxythiophene is 1-10; after stirring, the solution is centrifuged and washed with ethanol and ultrapure water, respectively, to obtain NiPc-based functionalized nanosheets NiPcNS.
3. An electrochemical biosensor based on biomimetic catalyst functionalized nanosheets for detecting organophosphorus pesticides, characterized in that: (1) mixing the dispersion of the CoPc-based functionalized nanosheet CoPcNS in claim 2 with a model enzyme and a chitosan solution, adding the mixture dropwise to the surface of a glassy carbon electrode, and allowing the mixture to stand and dry at room temperature to obtain an electrochemical biosensor for detecting organophosphorus pesticides; (2) immersing the electrochemical biosensor in an acetylthiocholine chloride solution, performing a constant potential scan at a working potential, and recording the current intensity i1; (3) taking out the electrochemical biosensor, washing it with a buffer solution, and then immersing it in a sample to be tested for incubation; (4) taking out the electrochemical biosensor, washing it with a buffer solution, and then immersing it in an acetylthiocholine chloride solution of the same concentration as in step (1), and recording the current intensity i2 by constant potential scanning at the same working potential. The inhibition rate I is (i1-i2) / i1, and a correlation curve between the inhibition rate and the concentration of the organophosphorus pesticide is obtained; (5) Calculate the content of organophosphorus pesticides in the sample to be analyzed by using the correlation curve between the inhibition rate and the concentration of the organophosphorus pesticides.
4. The preparation and use according to claim 3, characterized in that: The preparation method of the electrochemical biosensor in step (1) is as follows: polishing the surface of the glassy carbon electrode with aluminum oxide powder, ultrasonically cleaning it in deionized water and anhydrous ethanol in sequence, and drying it under nitrogen; dissolving chitosan in 0.5-4% acetic acid to obtain 2.5-10 mg mL -1 chitosan solution; chitosan solution and 0.2-1 mg mL -1 CoPcNS and model enzyme solution (0.1-0.4UμL -1 , dissolved in buffer solution) and mixed thoroughly; finally, the mixture was dropped onto a freshly cleaned glassy carbon electrode and dried at room temperature to obtain an electrochemical biosensor.
5. The preparation and use according to claim 3, characterized in that: The model enzyme in step (1) includes acetylcholinesterase and butyrylcholinesterase; the working potential in step (2) is 0-0.4V; the buffer solution in step (3) is a phosphate buffer solution, i.e., a mixed aqueous solution of Na2HPO4 and NaH2PO4 with equimolar concentrations of 20-100mmol / L, and its pH is 6-8; the incubation time in step (3) is 5-20min; the samples to be tested in step (3) are fruit and vegetable samples and water samples; the organophosphorus pesticides in step (3) include paraoxon, parathion, dichlorvos, and chlorpyrifos.
6. Preparation and application of an electrochemical sensor based on the biomimetic catalyst functionalized nanosheet for detecting hydrogen peroxide, characterized in that: The preparation and application of the electrochemical sensor comprises the following steps: (1) mixing a dispersion of the FePr-based functionalized nanosheet FePrNS in claim 2 with an aqueous solution of Nafion, and dripping the mixture onto the surface of a glassy carbon electrode, and allowing the mixture to stand and dry at room temperature to obtain an electrochemical sensor for detecting hydrogen peroxide; (2) immersing the electrochemical sensor in a buffer solution under the protection of nitrogen, and continuously dropping a standard solution of hydrogen peroxide into the buffer solution; performing a constant potential scan to obtain a current-time relationship curve; and obtaining a correlation curve between current intensity and hydrogen peroxide concentration based on the steady-state current corresponding to different concentrations of hydrogen peroxide; (3) The content of hydrogen peroxide in the sample to be analyzed is calculated using the correlation curve between the current intensity and the hydrogen peroxide concentration.
7. The preparation and use according to claim 6, characterized in that: The working potential in step (2) is -0.1-0.4V; the buffer solution in step (2) is a phosphate buffer solution, i.e., a mixed aqueous solution of Na2HPO4 and NaH2PO4 with equimolar concentrations of 20-100mmol / L, and its pH is 6-8.
8. A preparation and application of an electrochemical sensor based on the biomimetic catalyst functionalized nanosheet for detecting nitric oxide, characterized in that: The preparation and application of the electrochemical sensor comprises the following steps: (1) mixing a dispersion of the NiPc-based functionalized nanosheet NiPcNS in claim 2 with an aqueous solution of Nafion, and dripping the mixture onto the surface of a glassy carbon electrode, and allowing the mixture to stand and dry at room temperature to obtain an electrochemical sensor for detecting nitric oxide; (2) immersing the electrochemical sensor in a buffer solution under the protection of nitrogen, and continuously dropping a standard solution of nitric oxide into the buffer solution; performing a constant potential scan to obtain a current-time relationship curve; and obtaining a correlation curve between current intensity and nitric oxide concentration based on the steady-state current corresponding to different concentrations of nitric oxide; (3) The content of nitric oxide in the sample to be analyzed is calculated by using the correlation curve between the current intensity and the nitric oxide concentration.
9. The preparation and use according to claim 6 or 8, characterized in that: The preparation method of the electrochemical sensor in step (1) is as follows: polishing the surface of the glassy carbon electrode with aluminum oxide powder, ultrasonically cleaning it in deionized water and anhydrous ethanol in turn and drying it under nitrogen; adding 0.2-2 mg mL -1 The FePrNS or NiPcNS suspension was dropped onto a glassy carbon electrode and dried at room temperature to obtain the FePrNS or NiPcNS-based sensors.
10. The preparation and use according to claim 8, characterized in that: The working potential in step (2) is 0.5-1V; the buffer solution in step (2) is a phosphate buffer solution, i.e., a mixed aqueous solution of Na2HPO4 and NaH2PO4 with equimolar concentrations of 20-100 mmol / L, and its pH is 6-8.