阅读说明：本技术 用于胃液中多巴胺检测的电化学传感器及制备方法与应用 (Electrochemical sensor for detecting dopamine in gastric juice and preparation method and application thereof ) 是由 陈达 石宇晴 练美玲 于 2021-11-09 设计创作，主要内容包括：本发明属于电化学传感器技术领域,公开了一种用于胃液中多巴胺检测的电化学传感器及制备方法与应用。本发明公开的制备方法包括：(1)Nb-(2)C-MXene的制备；(2)NS-Nb-(2)C-MXene的制备；(3)NS-Nb-(2)C-MXene/Nafion修饰电极的制备；(4)基于NS-Nb-(2)C-MXene/Nafion的电化学多巴胺传感器的构建。通过简单的杂原子掺杂制备方法,本发明公开的氮、硫共掺杂Nb-(2)C/Nafion修饰电极具有良好的电化学活性、稳定性和重现性,氮、硫共掺杂协同增强了传感器的电化学响应信号,从而实现了酸性条件下胃液中多巴胺发快速、灵敏检测。(The invention belongs to the technical field of electrochemical sensors, and discloses an electrochemical sensor for detecting dopamine in gastric juice, and a preparation method and application thereof. The preparation method disclosed by the invention comprises the following steps: (1) nb 2 Preparing C-MXene; (2) NS-Nb 2 Preparing C-MXene; (3) NS-Nb 2 Preparing a C-MXene/Nafion modified electrode; (4) based on NS-Nb 2 And (3) constructing an electrochemical dopamine sensor of C-MXene/Nafion. The invention discloses a nitrogen and sulfur co-doped Nb by a simple heteroatom doping preparation method 2 The C/Nafion modified electrode has good electrochemical activity, stability and reproducibility, and nitrogen and sulfur codoping synergistically enhance the electrochemical response signal of the sensor, so that rapid and sensitive detection of dopamine in gastric juice under an acidic condition is realized.)

1. Electrochemical sensor for detecting dopamine in gastric juice, characterized in that the sensor uses NS-Nb₂C-MXene/Nafion/GCE is a working electrode, a platinum wire is a counter electrode, and a silver/silver chloride electrode is a reference electrode.

2. Electrochemical sensor for dopamine in gastric fluid detection according to claim 1, characterized in that the NS-Nb₂C-MXene has a two-dimensional layered structure.

3. The method for preparing an electrochemical sensor for detecting dopamine in gastric juice according to claim 1, comprising the steps of:

（1）Nb₂preparation of C-MXene

Adding Nb into 40-50% HF solution₂AlC powderReacting for 20-24 h under the condition of 20-25 ℃ and magnetic stirring at the speed of 700-800 r/min to obtain a corrosion product; continuously washing the corrosion product by using deionized water until the pH of the supernatant after centrifugation at 10000-20000 r/min is 6-7; washing with anhydrous ethanol for 5-7 times, and oven drying in vacuum oven to obtain Nb₂C, a base material;

（2）NS-Nb₂preparation of C-MXene

Nb prepared in the step (1)₂Grinding and mixing the powder C and thiourea uniformly, then putting the mixture into an atmosphere furnace, heating the mixture to 500-600 ℃ under the argon atmosphere, preserving the heat for 2-5 h, and then cooling the mixture to 20-25 ℃ along with the furnace; grinding the prepared material again, and washing with deionized water until the pH of the centrifuged supernatant is 6-7; drying the obtained powder to obtain NS-Nb₂C-MXene；

（3）NS-Nb₂Preparation of C-MXene/Nafion modified electrode

NS-Nb prepared in the step (2)₂Method for preparing NS-Nb by dispersing C-MXene powder in aqueous solution₂C-MXene suspension; carrying out ultrasonic treatment on a Nafion aqueous solution with the volume fraction of 2-8% for 10-15 min at the temperature of 20-25 ℃ to obtain a Nafion solution with the mass fraction of 1-2%; NS-Nb₂Mixing the C-MXene suspension and the Nafion solution in a volume ratio of 1: 1-1: 5, and then carrying out ultrasonic treatment for 30-35 min; transferring 6-8 mu L NS-Nb by using liquid transferring gun₂Dripping C-MXene/Nafion mixed solution on the surface of a glassy carbon electrode and airing to obtain NS-Nb₂C-MXene/Nafion/GCE modified electrode;

(4) based on NS-Nb₂Construction of C-MXene/Nafion electrochemical dopamine sensor

NS-Nb prepared by the step (3)₂C-MXene/Nafion/GCE is used as a working electrode, a platinum wire is used as a counter electrode, a silver/silver chloride electrode is used as a reference electrode, 5-10 muL dopamine solutions with different concentrations are added into PBS buffer solution with pH =2-10, a differential pulse voltammetry method is adopted for carrying out scanning test, and the scanning potential is-0.3-0.8V.

4. The method for preparing an electrochemical sensor for detecting dopamine in gastric juice as claimed in claim 3, wherein in the step (1), the electrochemical sensor is dried in the vacuum oven at 60-70 ℃ for 10-12 h.

5. The method for preparing an electrochemical sensor for detecting dopamine in gastric juice as claimed in claim 3, wherein in step (2), the Nb is₂The weight ratio of the C powder to the thiourea is (1-2) to (3-7).

6. The method for preparing an electrochemical sensor for detecting dopamine in gastric juice as claimed in claim 3, wherein, in the step (3), the NS-Nb is added₂The concentration of the C-MXene suspension is 5-7 g/L.

7. The method for preparing an electrochemical sensor for detecting dopamine in gastric juice as claimed in claim 3, wherein in the step (4), the concentration of the dopamine solution is 0.4-90 μmol/L.

8. Use of an electrochemical sensor for the detection of dopamine in gastric juice according to claim 1, in the preparation of a device for the detection of dopamine in gastric juice.

9. Use of an electrochemical sensor for dopamine in gastric fluid detection according to claim 8, characterized in that the pH of the detection environment for dopamine in gastric fluid detection is 3-4.

Technical Field

The invention belongs to the technical field of electrochemical sensors, and particularly relates to an electrochemical sensor for detecting dopamine in gastric juice, and a preparation method and application thereof.

Background

Dopamine is a catecholamine neurotransmitter which is most abundant in the central nervous system of human beings, plays an important regulation role in gastrointestinal motility, gastric acid secretion, oxygen supply of gastric mucosa blood flow and various digestive tract diseases, and is one of the protection factors which are currently involved in the gastrointestinal mucosa. Therefore, the realization of the quantitative detection of dopamine in a biological system, particularly the detection of dopamine in gastric juice under an acidic condition, has important significance for the health of human beings and the diagnosis, treatment and control of diseases.

In recent years, many studies have been conducted around highly sensitive and highly selective dopamine detection methods, such as high performance liquid chromatography, fluorescence spectroscopy, ultraviolet-spectrophotometer method, and capillary electrophoresis method. However, the detection method has the problems of complicated steps, expensive instruments and equipment, high cost and low sensitivity. The electrochemical sensor method has the characteristics of simple operation, high sensitivity and no need of advanced complex pretreatment, and becomes an ideal method for detecting dopamine. However, since the performance and stability of the sensor are required to be high in detection under acidic conditions, an electrochemical sensor based on dopamine in gastric juice is rarely reported. Therefore, it is urgently needed to provide a sensitive and stable electrochemical detection method for dopamine under acidic conditions.

Disclosure of Invention

In view of the above, the first objective of the present invention is to provide a dopamine electrochemical sensor that is sensitive and stable under acidic conditions.

In order to achieve the purpose, the invention adopts the following technical scheme:

an electrochemical sensor for detecting dopamine in gastric juice is composed of NS-Nb₂C-MXene/Nafion/GCE is a working electrode, a platinum wire is a counter electrode, and a silver/silver chloride electrode is a reference electrode.

Electrode materials are key factors affecting the analytical performance of electrochemical sensors. MXene is a two-dimensional (2D) early transition metal carbide and/or nitride-composed two-dimensional layered material, and is an excellent sensor electrode material due to excellent properties of a high-conductivity surface, a large specific surface area, abundant surface chemical groups, good hydrophilicity, adsorptivity, environmental stability and the like. However, MXene is in its primary stage for use in electrochemical sensing and has not been explored to a great extent. Most of the research is based on titanium carbide,in particular functionalized niobium carbide (Nb)₂C) The field of electrochemical sensing remains to be explored. While the method of modifying MXene intrinsic activity to improve the relevant electrochemical characteristics by introducing heteroatoms, polymers, other functional groups and other metal ions is an effective strategy.

The invention relates to a novel two-dimensional carbide nano material (Nb)₂C-MXene), improves the sensitivity and selectivity of the sensor, enhances the response signal of the electrochemical sensor, shortens the response time of the sensor and realizes the accurate detection of the concentration of the dopamine in gastric juice under an acidic condition by introducing nitrogen and sulfur heteroatoms.

Preferably, said NS-Nb₂C-MXene has a two-dimensional layered structure.

The second purpose of the present invention is to provide a method for preparing an electrochemical sensor for detecting dopamine in gastric juice as described above.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of the electrochemical sensor for detecting dopamine in gastric juice comprises the following steps:

（1）Nb₂preparation of C-MXene

Adding Nb into 40-50% HF solution₂AlC powder reacts for 20-24 hours under the condition of 20-25 ℃ and magnetic stirring at the speed of 700-; continuously washing the corrosion product by using deionized water until the pH of the supernatant after centrifugation at 10000-20000 r/min is 6-7; washing with anhydrous ethanol for 5-7 times, and oven drying in vacuum oven to obtain Nb₂C, a base material;

（2）NS-Nb₂preparation of C-MXene

Nb prepared in the step (1)₂Grinding and mixing the powder C and thiourea uniformly, then putting the mixture into an atmosphere furnace, heating the mixture to 500-600 ℃ under the argon atmosphere, preserving the heat for 2-5 h, and then cooling the mixture to 20-25 ℃ along with the furnace; grinding the prepared material again, and washing with deionized water until the pH of the centrifuged supernatant is 6-7; drying the obtained powder to obtain NS-Nb₂C-MXene；

（3）NS-Nb₂Preparation of C-MXene/Nafion modified electrode

NS-Nb prepared in the step (2)₂Method for preparing NS-Nb by dispersing C-MXene powder in aqueous solution₂C-MXene suspension; carrying out ultrasonic treatment on a Nafion aqueous solution with the volume fraction of 2-8% for 10-15 min at the temperature of 20-25 ℃ to obtain a Nafion solution with the mass fraction of 1-2%; NS-Nb₂Mixing the C-MXene suspension and the Nafion solution in a volume ratio of 1: 1-1: 5, and then carrying out ultrasonic treatment for 30-35 min; transferring 6-8 mu L NS-Nb by using liquid transferring gun₂Dripping C-MXene/Nafion mixed solution on the surface of a glassy carbon electrode and airing to obtain NS-Nb₂C-MXene/Nafion/GCE modified electrode;

(4) based on NS-Nb₂Construction of C-MXene/Nafion electrochemical dopamine sensor

NS-Nb prepared by the step (3)₂C-MXene/Nafion/GCE is used as a working electrode, a platinum wire is used as a counter electrode, a silver/silver chloride electrode is used as a reference electrode, 5-10 muL dopamine solutions with different concentrations are added into PBS buffer solution with pH =2-10, a differential pulse voltammetry method is adopted for carrying out scanning test, and the scanning potential is-0.3-0.8V.

Preferably, in the step (1), drying is carried out in the vacuum oven at 60-70 ℃ for 10-12 h.

Preferably, in step (2), the Nb is₂The weight ratio of the C powder to the thiourea is (1-2) to (3-7).

Preferably, in step (3), the NS-Nb₂The concentration of the C-MXene suspension is 5-7 g/L.

Preferably, in the step (4), the concentration of the dopamine solution is 0.4-90 [ mu ] mol/L.

A third object of the present invention is to provide an application of the electrochemical sensor for detecting dopamine in gastric juice as described above.

The sensor is applied to equipment for detecting dopamine in gastric juice.

Preferably, the pH value of the detection environment for detecting dopamine in gastric juice is 3-4.

Compared with the prior art, the invention has the beneficial effects that:

(1) NS-Nb₂The preparation method of C-MXene is simple, and Nb is added₂Mixing the C powder with thiourea and calcining at high temperature to obtain NS-Nb₂The C-MXene has an organ-shaped layered structure, and nitrogen and sulfur co-doping increases the interlayer spacing inside the nanosheet to obtain a higher specific surface area.

(2) The invention adopts NS-Nb₂The electrochemical sensor prepared by using C-MXene as a substrate electrode material has stronger electron transfer capability, and nitrogen and sulfur co-doping synergistically improves the electrochemical activity of the sensor and enhances the response signal of the electrochemical sensor.

(3) The electrochemical sensor prepared by the invention has the advantages of simple operation, low detection limit and high sensitivity.

(4) The electrochemical dopamine sensor prepared by the invention has excellent reproducibility and stability, is suitable for detecting dopamine in gastric juice under an acidic condition, and overcomes the defects of poor stability and low performance of a common sensor under an acidic condition.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 shows NS-Nb prepared in example 1 of the present invention₂SEM image of C-MXene.

FIG. 2 shows Nb prepared in example 1 of the present invention₂C-MXene and NS-Nb₂XRD pattern of C-MXene.

FIG. 3 shows Nb prepared in example 1 of the present invention₂Nitrogen adsorption profile of C-MXene.

FIG. 4 shows Nb prepared in example 1 of the present invention₂C/GCE and NS-Nb₂Cyclic voltammogram of C/GCE.

FIG. 5 is a representation of NS-Nb prepared in accordance with example 2 of the present invention₂Oxidation peak current and pH in cyclic voltammetry curve of dopamine solution under different pH values by C/Nafion/GCEA value relationship graph.

FIG. 6 shows NS-Nb prepared in example 2 of the present invention₂And the differential pulse voltammetry curve and the linear fitting relation graph of the peak current and the corresponding dopamine concentration of the C/Nafion/GCE in dopamine solutions with different concentrations.

FIG. 7 is NS-Nb prepared in example 2 of the invention₂And C-MXene/Nafion/GCE detects the repeatability and stability of dopamine.

FIG. 8 is a schematic view of the preparation steps disclosed in examples 1 to 2 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

（1）Nb₂Preparation of C-MXene

Adding Nb into 40 percent HF solution₂AlC powder reacts for 24 hours under the condition of magnetic stirring at the speed of 700 r/min at the temperature of 25 ℃ to obtain a corrosion product; continuously washing the corrosion product by deionized water until the pH value of the supernatant is 7; washing with anhydrous ethanol for 5 times, drying at 60 deg.C for 12 hr to obtain Nb₂And C, a base material.

（2）NS-Nb₂Preparation of C-MXene

100 mg of Nb prepared in the step (1)₂Grinding and uniformly mixing the powder C and 300 mg of thiourea, then putting the mixture into an atmosphere furnace, heating the mixture to 500 ℃ under the argon atmosphere, preserving the heat for 3 hours, and then cooling the mixture to 25 ℃ along with the furnace; grinding the prepared material again, and continuously cleaning the ground material by using deionized water until the pH value of the supernatant is 7; drying the obtained powder to obtain the nitrogen and sulfur co-doped Nb₂C nano powder NS-Nb₂C-MXene。

FIG. 1 shows NS-Nb prepared in example 1 of the present invention₂Scanning electron microscopy of C-MXene. NS-Nb as shown in FIG. 1₂C-MXene has an organ-shaped two-dimensional layered structure, has a large specific surface area, and can increase the electrochemical active sites on the surface of the material.

FIG. 2 shows Nb prepared in example 1 of the present invention₂C-MXene and NS-Nb₂X-ray diffraction pattern of C-MXene. As can be seen from FIG. 2, Nb₂The main diffraction peaks of the C material appear on the crystal planes of (100), (002), (101), (102), (110), (112) and (201), which indicates that Nb is₂The successful preparation of C-MXene.

FIG. 3 shows Nb prepared in example 1 of the present invention₂Nitrogen adsorption profile of C-MXene. The resulting NS-Nb can be seen₂C-MXene has a higher specific surface area.

（3）NS-Nb₂Preparation of C-MXene/Nafion modified electrode

NS-Nb prepared in the step (2)₂Method for preparing NS-Nb by dispersing C-MXene powder in aqueous solution₂C-MXene suspension; carrying out ultrasonic treatment on a Nafion aqueous solution with the volume fraction of 5% for 10min at 25 ℃ to obtain a Nafion solution with the mass fraction of 2%; NS-Nb₂Mixing the C-MXene suspension and the Nafion solution in a volume ratio of 1:1, and then carrying out ultrasonic treatment for 30 min; transferring 8 mu L NS-Nb by using liquid transferring gun₂Dripping C-MXene/Nafion mixed solution on the surface of a glassy carbon electrode and airing to obtain NS-Nb₂C-MXene/Nafion/GCE。

FIG. 4 is a graph showing the electrochemical behavior of a modified electrode on dopamine in example 1 of the present invention; wherein, the electrolyte solution in figure 4a is 0.1 mol/L PBS solution containing 100 mu mo1/L dopamine, and the electrolyte solution in figure 4b is 5 mmol/L [ Fe (CN)₆]^3-/4- And 0.1 mol/L KCl in water at a sweep rate of 100 mV/s. As shown in FIG. 4a, with multiple layers of Nb₂C nanosheet and single layer Nb₂NS-Nb of C nanosheet₂The C nanosheet modified electrode has the most obvious oxidation-reduction current peak of dopamine. This is because the doped nitrogen and sulfur are Nb₂The C nano-sheet provides more active sites and improves the electrochemical performance. As can be seen in FIG. 4b, NS-Nb₂The peak-to-peak difference of the C modified electrode is minimum, the current value is maximum, and the NS-Nb is shown₂The surface of the C nano-sheet electrode has the maximum electron transfer speedRate and excellent conductivity.

(4) Based on NS-Nb₂Construction of C-MXene/Nafion electrochemical dopamine sensor

The NS-Nb₂C-MXene/Nafion/GCE is a working electrode, a platinum wire is a counter electrode, and a silver/silver chloride electrode is a reference electrode. 10 muL of dopamine solutions with different concentrations are added into a PBS buffer solution (pH = 3), a differential pulse voltammetry is adopted for scanning test, and the scanning potential is-0.3-0.8V.

Example 2

（1）Nb₂Preparation of C-MXene

Adding Nb into 50% HF solution₂The AlC powder reacts for 20 hours under the condition of magnetic stirring at the speed of 800 r/min at the temperature of 20 ℃ to obtain a corrosion product; continuously washing the corrosion product by deionized water until the pH value of the supernatant is 6; washing with anhydrous ethanol for 7 times, drying at 60 deg.C for 10 hr to obtain Nb₂And C, a base material.

（2）NS-Nb₂Preparation of C-MXene

200 mg of Nb prepared in the step (1)₂Grinding and uniformly mixing the powder C and 700 mg of thiourea, then putting the mixture into an atmosphere furnace, heating the mixture to 600 ℃ under the argon atmosphere, preserving the heat for 4 hours, and then cooling the mixture to 20 ℃ along with the furnace; grinding the prepared material again, and continuously cleaning the ground material by using deionized water until the pH value of the supernatant is 6; drying the obtained powder to obtain NS-Nb₂C-MXene。

（3）NS-Nb₂Preparation of C-MXene/Nafion modified electrode

NS-Nb prepared in the step (2)₂Method for preparing NS-Nb by dispersing C-MXene powder in aqueous solution₂C-MXene suspension; carrying out ultrasonic treatment on a Nafion aqueous solution with the volume fraction of 6% for 15 min at the temperature of 20 ℃ to obtain a Nafion solution with the mass fraction of 1%; NS-Nb₂Mixing the C-MXene suspension and the Nafion solution in a volume ratio of 1:5, and performing ultrasonic treatment for 35 min; transferring 6 mu L NS-Nb by using liquid transferring gun₂Dripping C-MXene/Nafion mixed solution on the surface of a glassy carbon electrode and airing to obtain NS-Nb₂The electrode NS-Nb2C-MXene/Nafion/GCE is modified by C-MXene/Nafion.

(4) Based on NS-Nb₂Construction of C-MXene/Nafion electrochemical dopamine sensor

The NS-Nb₂C-MXene/Nafion/GCE is a working electrode, a platinum wire is a counter electrode, and a silver/silver chloride electrode is a reference electrode. 6 mu L of dopamine solutions with different concentrations are added into a PBS buffer solution (pH = 3), a differential pulse voltammetry is adopted for scanning test, and the scanning potential is-0.3-0.8V.

FIG. 5 shows NS-Nb₂Cyclic voltammetry curves of C-MXene/Nafion/GCE in dopamine solutions at different pH values, wherein the pH values are 7.0, 6.0, 5.0, 4.0 and 3.0 from left to right respectively. As can be seen from the graph, the peak current of dopamine shows a gradual increase phenomenon as the pH value decreases. The peak current of dopamine reached a maximum when the pH of the buffer was 3, with the most pronounced response, so pH =3 was chosen as the optimum pH for the experiment. The oxidation peak potential Ep of dopamine and the pH value have good linear relation, and the linear regression equation is as follows: ep (V) =0.691-0.053pH (R)²=0.998), the linear regression equation of which is the nernst equation: epa (mv) = E₀-59.2(m/n)pH (25℃，E₀Is the standard potential, m is the proton transfer number, n is the electron transfer number). Therefore, the slope of the linear equation is-53, the slope of the linear equation is close to-59.2 of the Nernst equation, and m/n is close to 1, which shows that the redox reaction of the dopamine on the electrode is a quasi-reversible process of protons such as an isoelectron.

FIG. 6 is NS-Nb₂The differential pulse voltammetry response curve of C-MXene/Nafion/GCE to different dopamine concentrations is 0.4, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80 and 90 [ mu ] mo1/L respectively from bottom to top. As can be seen from fig. 6a, the peak current of dopamine increases with increasing dopamine concentration. As can be seen from FIG. 6b, NS-Nb₂C-MXene/Nafion/GCE shows a wide linear concentration range (0.4-90 mu mol/L), and the linear regression equation is expressed as: ipa (mu a) = 0.71+0.35C_DA(mu M), the detection limit (S/N = 3) is 0.18 mu mol/L.

FIG. 7 shows NS-Nb₂Repeatability and stability of C-MXene/Nafion/GCE. By means ofPreparation of group 5 NS-Nb in example 2₂C-MXene/Nafion/GCE, and the relative standard deviation of the results obtained by five times of determination is 0.33% as shown in figure 7a when the dopamine solution with the concentration of 100 mumol/L is detected. NS-Nb prepared in example 2 was used₂C-MXene/Nafion/GCE detects the dopamine solution containing 100 mu mol/L, the solution is cleaned after detection and stored for 7 days at room temperature, the electrode is used for measurement every day within 7 days, and the oxidation peak response current of the dopamine is kept above 95.9% of the initial measurement peak current value (figure 7 b).

The preparation steps of the invention in examples 1-2 are shown in FIG. 8.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.