Dopamine electrochemical sensor based on gcp350 / mos2 / mwcnts composite material modification

Abstract

The application discloses a dopamine electrochemical sensor based on a GCP350 / MoS2 / MWCNTs composite material, relates to the technical field of electrochemical sensors, and has the technical scheme as follows: S1, synthesis of GCP350; S2, synthesis of MoS2 / MWCNTs; S3, establishment of a GCP350 / MoS2 / MWCNTs / GCE electrochemical sensing platform; and S4, electrochemical detection. The electrochemical sensor established by the method is simple to operate, simple in process, low in cost and high in sensitivity. The electrochemical sensing platform established for accurate quantitative analysis and detection of catechin can quickly and accurately detect catechin solution.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical sensors, more particularly, it relates to a dopamine electrochemical sensor based on GCP350 / MoS2 / MWCNTs composite material. BACKGROUND

[0002] Catechin (CA) is a natural flavonoid with multiple biological activities. It mainly exists in plants, fruits, vegetables, especially in green tea. Catechin is a well-known antioxidant and can be used to treat or prevent some health problems, including cardiovascular disease, inflammation, diabetes, obesity and other chronic diseases. However, excessive intake of catechin can also increase health risks. Therefore, accurate quantitative analysis of catechin is necessary and important. At present, the quantitative detection of catechin still relies on traditional methods such as high performance liquid chromatography, gas chromatography, spectrophotometry and mass spectrometry. However, these methods also have some disadvantages, such as complex operation and pretreatment process, low analysis efficiency and expensive equipment, which limit their wide application. Therefore, simple electrochemical sensing technology with simple process, low cost and high sensitivity has attracted the attention of a large number of researchers, and it is necessary to develop an electrochemical sensing platform for detecting catechin.

[0003] For electrochemical sensors, suitable electrode materials play an important role and can greatly affect the detection effect. Metal-organic frameworks (MOFs) have been widely used as a new inorganic-organic hybrid material. Due to its adjustable pore size and MOFs structure, high specific surface area and pore volume, it has recently shown its unique advantages and great potential in energy storage and conversion, such as supercapacitors, lithium ion batteries (LIBs), lithium-sulfur batteries, lithium-oxygen batteries, CO2 reduction, oxygen evolution and reduction reactions, and so on. However, the physical and chemical properties of the material will change greatly. Due to the special size dependence of nanomaterials, they are used in various fields, including energy-related applications. Recent studies have shown that by reducing the size of MOFs to nanoscale (usually size greater than 50 nm), higher specific surface area and more active sites can be obtained compared to bulk particles, which can greatly enhance the electrochemical performance.

[0004] Graphene-like molybdenum disulfide (MoS2) has attracted significant interest in the family of dichalcogenides (TMDs) due to its weak interlayer van der Waals interactions, good chemical and thermal stability, and unique structural versatility at a low cost. Among various types of TMDs, graphene-like MoS2 is also considered as an inorganic nanomaterial with electrochemical activity due to its large surface area, good electrochemical properties and surface modification potential. However, low electronic conductivity and oxidative degradation under environmental conditions limit the practical application of MoS2 in electrochemical devices and chemical / biological sensors. Hybridization of graphene-like MoS2 with conductive materials is an effective method to improve the electrocatalytic performance. Hybridization modulates the physical and chemical properties of MoS2 and creates diversified functions among different components through synergistic effects, thereby enhancing the solution processability of MoS2, improving its mechanical properties and the electronic conductivity of its hybrids. Multi-walled carbon nanotubes (MWCNTs) are a kind of fibrous carbon-based nanomaterials with a large specific surface area, high electrical conductivity, electrocatalytic activity and adsorption properties, which can improve the electronic transmission capacity and the performance of electrochemical sensors. In addition, carboxylated multi-walled carbon nanotubes will improve their water solubility and make them have better application in the field of electrochemical sensing. SUMMARY

[0005] The purpose of the present application is to provide a dopamine electrochemical sensor based on GCP350 / MoS2 / MWCNTs composite material modification, which is used for precise quantitative analysis and detection of electrochemical sensing platform of catechin.

[0006] The above technical purpose of the present application is realized by the following technical scheme: a dopamine electrochemical sensor based on GCP350 / MoS2 / MWCNTs composite material modification, comprising the following step process:

[0007] S1: Synthesis of GCP350; a certain amount of graphite powder was added to sulfuric acid at low temperature, then a certain amount of potassium permanganate was slowly added to the above mixture, stirring for 2 h; then the reaction system was heated to 35°C, and the reaction was continued for 2 h; the mixture was diluted with DI water, then the reaction system was continued to stir in ice water bath for 1 h, and DI water was added again for dilution; H2O2 and HCl were added to remove KMnO4 and metal ions, and the solution was washed to neutral with DI water, and the collected solid was dried at 60°C to obtain the product GO; then, a certain amount of GO and potassium hexacyanocobaltate were dissolved in deionized water, treated under magnetic stirring and ultrasonic for 10 minutes and 5 minutes respectively; a certain amount of cobalt chloride solution was poured into it, then stirred for 1 hour; a certain amount of ammonium persulfate and pyrrole was then added to the above solution, and then stirred overnight to coat polypyrrole; centrifuged three times, dried overnight to obtain GCP; finally, GCP was gradually heated to 350°C at a heating rate of 10°C / min, and kept in air for 2 hours to obtain GCP350;

[0008] S2: Synthesis of MoS2 / MWCNTs; MWCNTs were dispersed in DMF and ultrasonicated for 2 hours to disperse uniformly; sodium molybdate and thiourea were added and stirred for 30 minutes, then the mixture was transferred to a reaction kettle and kept at 200°C for 12 h; after the system cooled to room temperature, the precipitate was filtered out, washed repeatedly and dried for 12 h to obtain MoS2 / MWCNTs;

[0009] S3: Construction of GCP350 / MoS2 / MWCNTs / GCE electrochemical sensing platform; the glassy carbon electrode was physically cleaned with different specifications of alumina powder until the surface was smooth, then the surface was washed with anhydrous ethanol and ultrapure water alternately, and finally dried under an infrared lamp to obtain a clean glassy carbon electrode; GCP350 and MoS2 / MWCNTs were dispersed in ultrapure water and treated under ultrasonic for 6 hours to disperse uniformly; the above dispersion was mixed in a certain proportion and treated under ultrasonic for 12 hours to obtain GCP350 / MoS2 / MWCNTs composite dispersion; the above liquid was taken with a pipette and drop-coated on the surface of the glassy carbon electrode and dried;

[0010] S4: Electrochemical detection; the detection of the electrochemical part was carried out on a CHI660 electrochemical workstation, a conventional three-electrode working system was adopted, in which the auxiliary electrode was a platinum wire electrode, the reference electrode was a saturated AgCl solution filled electrode, and the prepared modified electrode was the working electrode; the electrolyte solution used in the electrochemical detection part was 0.1M phosphate buffer solution (PBS), and the detection was always carried out in a nitrogen atmosphere; the potential range of the cyclic voltammetry (CV) was set to-0.2V-0.6V, and the scan rate was 100mV·s-1; wherein the electrochemical impedance experiment (EIS) was carried out in a 1.0M potassium ferricyanide / potassium ferrocyanide mixed solution containing 0.1M potassium chloride.

[0011] The application is further provided that: in step S1, 0.4g of graphite powder is added to sulfuric acid at low temperature, then 1.6g of potassium permanganate is slowly added to the above mixture, and stirred for 2h; then the reaction system is heated to 35℃, and the reaction is continued for 2h; the mixture is diluted with 20mL of DI water, then the reaction system is continuously stirred in an ice water bath for 1h, and diluted again with 60mL of DI water; H2O2 and HCl are added to remove KMnO4 and metal ions, and the solution is washed to neutral with DI water, and the collected solid precipitate is dried at 60℃ to obtain the product GO; then, 40mg of GO and 0.2mL of potassium hexacyanocobaltate (0.5M) are dissolved in 80mL of deionized water, and then treated under magnetic stirring and ultrasonic wave for 10min and 5min respectively; 2mL of cobalt chloride solution (CoCl2, 0.5M) is poured into it, and then stirred for 1h; 120mg of ammonium persulfate and 120μL of pyrrole are then added to the above solution, and then continuously stirred overnight to coat polypyrrole; centrifuged three times, dried overnight to obtain GCP; finally, the GCP is gradually heated to 350℃ at a heating rate of 10℃ / min, and kept in air for 2h to obtain GCP350.

[0012] The application is further provided that: in step S2, 5mg of MWCNT is dispersed in 30mL of DMF, and ultrasonically treated for 2h to disperse uniformly; 0.023g of sodium molybdate and 0.024g of thiourea are added, and stirred for 30min; then the above mixture is transferred to a reaction kettle, and kept at 200℃ for 12h; after the system is cooled to room temperature, the precipitate is filtered out, repeatedly washed, and dried for 12h to obtain MoS2 / MWCNTs.

[0013] The application is further provided that: in the step S3, the glassy carbon electrode is physically cleaned by different specifications of alumina powder to make the surface smooth, then the surface is cleaned by anhydrous ethanol and ultrapure water alternately, and finally dried under an infrared lamp to obtain a clean glassy carbon electrode; 2 mg of GCP350 and MoS2 / MWCNTs are taken and dispersed in 1 ml of ultrapure water, and treated under ultrasonic for 6 hours to make them uniformly dispersed; the above dispersion liquid is mixed in a certain proportion, and treated under ultrasonic for 12 hours to obtain a GCP350 / MoS2 / MWCNTs composite material dispersion liquid; 6 microliters of the above liquid is taken by a pipette, and dropped and coated on the surface of the glassy carbon electrode and dried.

[0014] In summary, the application has the following beneficial effects: the electrochemical sensor built by the method of the application has simple operation, simple process, low cost and high sensitivity. The electrochemical sensing platform built for accurate quantitative analysis and detection of catechin can quickly and accurately detect catechin solution. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the preparation process of the sensor in the embodiment of the application;

[0016] Figure 2 is the electrochemical impedance spectrum of different modified electrodes in the embodiment of the application;

[0017] Figure 3 is the CV response graph of different modified electrodes to 0.5 mu M catechin in the embodiment of the application;

[0018] Figure 4 is the DPV graph of GCP350 / MoS2 / MWCNTs / GCE to catechin with different concentrations in the embodiment of the application;

[0019] Figure 5 is the working curve of GCP350 / MoS2 / MWCNTs / GCE for catechin detection in the embodiment of the application. DETAILED DESCRIPTION

[0020] The following will be described in detail in combination with the accompanying Figures 1-5 The application will be further described in detail.

[0021] Embodiment: a dopamine electrochemical sensor based on GCP350 / MoS2 / MWCNTs composite material modification, as shown in the figure, the preparation process is as follows: Figures 1-5

[0022] Synthesis of GCP350

[0023] ​0.4 g of graphite powder was added to sulfuric acid at low temperature, then 1.6 g of potassium permanganate was slowly added to the above mixture, stirring for 2 h; then the reaction system was heated to 35 °C, and the reaction was continued for 2 h; the mixture was diluted with 20 mL of DI water, then the reaction system was continuously stirred in an ice water bath for 1 h, and diluted again with 60 mL of DI water; H2O2 and HCl were added to remove KMnO4 and metal ions, and the solution was washed to neutral with DI water, and the collected solid was dried at 60 °C to obtain the product GO; then, 40 mg of GO and 0.2 mL of potassium hexacyanocobaltate (0.5 M) were dissolved in 80 mL of deionized water, then treated under magnetic stirring and ultrasonic wave for 10 minutes and 5 minutes, respectively; 2 mL of cobalt chloride solution (CoCl2, 0.5 M) was poured into it, then stirred for 1 hour; 120 mg of ammonium persulfate and 120 μL of pyrrole were then added to the above solution, and then continuously stirred overnight to coat polypyrrole; centrifuged three times, dried overnight to obtain GCP; finally, GCP was gradually heated to 350 °C at a heating rate of 10 °C / min and kept in air for 2 hours to obtain GCP350.

[0024] Synthesis of MoS2 / MWCNTs

[0025] 5 mg of MWCNTs were dispersed in 30 mL of DMF and ultrasonically treated for 2 hours to disperse uniformly; 0.023 g of sodium molybdate and 0.024 g of thiourea were added and stirred for 30 minutes; then the mixture was transferred to a reaction kettle and kept at 200 °C for 12 h; after the system cooled to room temperature, the precipitate was filtered out, washed repeatedly, and dried for 12 h to obtain MoS2 / MWCNTs.

[0026] Establishment of GCP350 / MoS2 / MWCNTs / GCE electrochemical sensing platform

[0027] The glassy carbon electrode was physically cleaned with different specifications of aluminum oxide powder to make the surface smooth, then the surface was washed with anhydrous ethanol and ultrapure water alternately, and finally dried under an infrared lamp to obtain a clean glassy carbon electrode; 2 mg of GCP350 and MoS2 / MWCNTs were dispersed in 1 mL of ultrapure water, and ultrasonically treated for 6 hours to disperse uniformly; the above dispersion was mixed in a certain proportion and treated under ultrasonic condition for 12 hours to obtain GCP350 / MoS2 / MWCNTs composite dispersion; 6 μL of the above liquid was taken with a pipette and dropped on the surface of the glassy carbon electrode and dried.

[0028] Electrochemical detection

[0029] The detection of electrochemical part was carried out on CHI660 electrochemical workstation, using conventional three-electrode system, in which the auxiliary electrode was platinum wire electrode, the reference electrode was saturated AgCl solution filled electrode, and the prepared modified electrode was working electrode; the electrolyte solution used in electrochemical detection part was 0.1M phosphate buffer solution (PBS), and the detection was always carried out in the atmosphere of nitrogen; the potential range of cyclic voltammetry (CV) was set to-0.2V-0.6V, and the scan rate was 100mV·s-1; wherein the electrochemical impedance experiment (EIS) was carried out in 1.0M potassium ferricyanide / potassium ferrocyanide mixed solution containing 0.1M potassium chloride.

[0030] Electrochemical characterization of catechin on different electrodes

[0031] Figure 2 The Nyquist curves of different modified electrodes are shown in sequence, and it can be clearly seen that the diameter of the Nyquist curve of bare GCE is larger, indicating that its electron transfer ability is the worst and the resistance is the largest, the curve curvature radius of GCP350 is much smaller, but it is still relatively obvious, and the conductivity cannot meet the detection requirements. The radius of the EIS curve of MoS2 / MWCNTs is almost a straight line, indicating that its electron transfer rate is faster and has excellent conductivity. After GCP350 and MoS2 / MWCNTs are combined together, the corresponding curve tends to be a straight line, because the combination of the two greatly reduces the polarization resistance and improves the electron transfer rate on the electrode surface. In summary, it is fully proved that the composite electrode has been successfully constructed.

[0032] The electrochemical response of catechin on the surface of different modified electrodes was tested by cyclic voltammetry (CV), and the experiment was carried out in 0.1M PBS (pH=7.0) solution, and the concentration of catechin was 0.5μM / L, and the experimental results are shown in Figure 3 The peak current value of the unmodified glassy carbon electrode for the detection of 0.5μM catechin is 0.89μA, while the peak current value of GCP350 / GCE is 2.987μA, the response peak current value of MoS2 / MWCNTs / GCE is 7.68μA, and the response current of the composite material GCP350 / MoS2 / MWCNTs is 14.7μA. This is because MoS2 / MWCNTs can improve the conductivity of the material, and GCP350 has a large specific surface area and certain adsorption capacity, so that catechin can be adsorbed on the electrode surface in large quantities, and the synergistic effect of the two makes the electrochemical response signal of catechin on the GCP350 / MoS2 / MWCNTs / GCE sensing platform reach 14.7μA, which is 1.9 times of GCP350, 4.9 times of GCP350, and 16.5 times of GCE.

[0033] Under the optimal conditions, the standard working curve of catechin was studied by differential pulse voltammetry (DPV). The working electrode GCP350 / MoS2 / MWCNTs / GCE was placed in 0.1M phosphate buffer solution with pH of 7.0, and a series of standard catechin solutions with different concentrations were detected, and the experimental results are shown in Figure 4 As the concentration of CA in the PBS solution increased, the electrochemical signal generated by the working electrode gradually increased. The concentration of CA was fitted with the value of the electrical signal, and it was found that it showed two linear relationships in the concentration range of 5nM to 200nM and 200nM to 1.8μM Figure 5 respectively. The fitting equations of the two linear relationships are as follows:

[0034] Ip1(μA)=0.1391(nM)+0.5504(R 2 =0.9966)

[0035] Ip2(μA)=0.0531C(nM)+15.563(R 2 =0.991)

[0036] Under the condition of S / N=3, it was calculated that the lowest detection limit (LOD) of the sensing platform for catechin was 1.78nM. Therefore, a new type of catechin electrochemical sensor was successfully constructed.

[0037] By using green tea beverage purchased from a local supermarket as a real sample detection object, the ability of the constructed electrochemical sensing platform to test catechin actual samples was tested. The experimental results are shown in Table 1, and it is calculated that the recovery rate is in the range of 98% to 103%, and the relative standard deviation is between 0.77% and 3.25%. The results show that the catechin sensor we constructed can be successfully used for the detection of actual samples.

[0038] Table 1 Test of actual samples

[0039]

[0040] It is shown that the sensor platform built by the method can be used for the detection of catechin in actual samples, and good experimental results can be obtained.

[0041] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing a dopamine electrochemical sensor based on GCP350 / MoS2 / MWCNTs composite material, characterized in that, The method comprises the following steps: S1: synthesis of GCP350; a certain amount of graphite powder is added into sulfuric acid at low temperature, and then a certain amount of potassium permanganate is slowly added into the mixture, and stirred for 2 h; then the reaction system is heated to 35°C, and the reaction is continued for 2 h; the mixture is diluted with DI water, and then the reaction system is continuously stirred in an ice water bath for 1 h, and DI water is added again for dilution; H2O2 and HCl are added to remove KMnO4 and metal ions, and the solution is washed to neutral with DI water, and the collected solid is dried at 60°C to obtain the product GO; then, a certain amount of GO and potassium hexacyanocobaltate are dissolved in deionized water, and treated under magnetic stirring and ultrasonic wave for 10 minutes and 5 minutes respectively; a certain amount of cobalt chloride solution is poured into it, and then stirred for 1 hour; a certain amount of ammonium persulfate and pyrrole are then added to the solution, and then continuously stirred overnight to coat polypyrrole; centrifuged three times, dried overnight, to obtain GCP; finally, the GCP is gradually heated to 350°C at a heating rate of 10°C / min, and kept in air for 2 hours to obtain GCP350; S2: synthesis of MoS2 / MWCNTs; MWCNTs are dispersed in DMF and ultrasonically treated for 2 hours to disperse uniformly; sodium molybdate and thiourea are added and stirred for 30 minutes, and then the mixture is transferred to a reaction kettle and kept at 200°C for 12 h; after the system is cooled to room temperature, the precipitate is filtered out, washed repeatedly, and dried for 12 h to obtain MoS2 / MWCNTs; S3: construction of GCP350 / MoS2 / MWCNTs / GCE electrochemical sensing platform; the glassy carbon electrode is physically cleaned with different specifications of alumina powder until the surface is smooth, and then the surface is washed with anhydrous ethanol and ultrapure water alternately, and finally dried under an infrared lamp to obtain a clean glassy carbon electrode; GCP350 and MoS2 / MWCNTs are dispersed in ultrapure water respectively, and treated under ultrasonic wave for 6 hours to disperse uniformly; the dispersion liquid is mixed in a certain proportion, and treated under ultrasonic wave for 12 hours to obtain a GCP350 / MoS2 / MWCNTs composite material dispersion liquid; the above composite material dispersion liquid is taken with a pipette, and dropped and coated on the surface of the glassy carbon electrode, and dried; S4: Electrochemical detection; The detection of electrochemical part was carried out on CHI660 electrochemical workstation, using three-electrode system, in which the auxiliary electrode was platinum wire electrode, the reference electrode was saturated AgCl solution filled electrode, and the prepared modified electrode was working electrode; The electrolyte solution used in electrochemical detection part was 0.1 M phosphate buffer solution (PBS), and the detection was always carried out in the atmosphere of nitrogen; The potential range of cyclic voltammetry (CV) was set to-0.2 V - 0.6 V, and the scan rate was 100 mV·s -1 ; wherein the electrochemical impedance experiment (EIS) was carried out in 1.0 M potassium ferricyanide / potassium ferrocyanide mixed solution containing 0.1 M potassium chloride.

2. The method for preparing a dopamine electrochemical sensor based on GCP350 / MoS2 / MWCNTs composite material according to claim 1, characterized in that: In the step S1, 0.4 g of graphite powder was added to sulfuric acid at low temperature, and then 1.6 g of potassium permanganate was slowly added to the mixture, and stirred for 2 h; then the reaction system was heated to 35°C, and the reaction was continued for 2 h; the mixture was diluted with 20 mL of DI water, and then the reaction system was continuously stirred in an ice water bath for 1 h, and diluted again by adding 60 mL of DI water; H2O2 and HCl were added to remove KMnO4 and metal ions, and the solution was washed to neutral with DI water, and the collected solid was dried at 60°C to obtain the product GO; then, 40 mg of GO and 0.2 mL of 0.5 M potassium hexacyanocobaltate solution were dissolved in 80 mL of deionized water, and then treated under magnetic stirring and ultrasonic wave for 10 minutes and 5 minutes, respectively; 2 mL of 0.5 M cobalt chloride solution was poured into it, and then stirred for 1 hour; 120 mg of ammonium persulfate and 120 μL of pyrrole were then added to the solution, and then continuously stirred overnight to coat polypyrrole; centrifuged three times, dried overnight, to obtain GCP; finally, the GCP was gradually heated to 350°C at a heating rate of 10°C / min, and kept in air for 2 hours to obtain GCP350.

3. The method for preparing a dopamine electrochemical sensor based on GCP350 / MoS2 / MWCNTs composite material according to claim 1, characterized in that: In the step S2, 5 mg of MWCNT was dispersed in 30 mL of DMF, and ultrasonically treated for 2 hours to disperse uniformly; 0.023 g of sodium molybdate and 0.024 g of thiourea were added, and stirred for 30 minutes; then the mixture was transferred to a reaction kettle, and kept at 200°C for 12 h; after the system was cooled to room temperature, the precipitate was filtered out, washed repeatedly, and dried for 12 h to obtain MoS2 / MWCNTs.

4. The method for preparing a dopamine electrochemical sensor based on GCP350 / MoS2 / MWCNTs composite material according to claim 1, characterized in that: In the step S3, the glassy carbon electrode was physically cleaned with different specifications of alumina powder to make the surface smooth, and then the surface was alternately cleaned with anhydrous ethanol and ultrapure water, and finally dried under an infrared lamp to obtain a clean glassy carbon electrode; 2 milligrams of GCP350 and MoS2 / MWCNTs were taken respectively, and dispersed in 1 milliliter of ultrapure water, and treated under ultrasonic wave for 6 hours to disperse uniformly; the dispersion was mixed in a certain proportion, and treated under ultrasonic wave for 12 hours to obtain a GCP350 / MoS2 / MWCNTs composite material dispersion; 6 microliters of the above composite material dispersion was taken with a pipette, and dropped on the surface of the glassy carbon electrode, and dried.

Images