CN113804738A

CN113804738A - Polyaniline-loaded cuprous oxide sensing electrode and preparation thereof

Info

Publication number: CN113804738A
Application number: CN202110991182.3A
Authority: CN
Inventors: 刘锡尧; 赵文昌; 应少明; 李萍; 林玲玲
Original assignee: Ningde Normal University
Current assignee: Ningde Normal University
Priority date: 2021-08-26
Filing date: 2021-08-26
Publication date: 2021-12-17
Anticipated expiration: 2041-08-26
Also published as: CN113804738B

Abstract

The invention provides a polyaniline loaded cuprous oxide sensing electrode and a preparation method thereof, wherein the preparation method comprises the following steps: s1, dispersing aniline monomer in dichloromethane; s2, sequentially adding an N-methyl pyrrolidone aqueous solution and camphorsulfonic acid under the stirring condition to react at room temperature; s3, slowly adding an ammonium persulfate aqueous solution into the reaction solution, standing for reaction, separating dichloromethane at the lower layer, and filtering the residual solution to obtain a solid product; s4, cleaning and drying the solid product to obtain camphorsulfonic acid doped PANI nano powder; s5, dispersing the camphorsulfonic acid doped PANI nano powder into glycol solution, adding copper sulfate pentahydrate, PVP, sodium hydroxide solution and glucose aqueous solution in sequence, stirring for reaction, continuing stirring for reaction at 80 ℃, filtering, washing and drying the product after the reaction is finished to obtain PANI-Cu₂O nano powder; followed by PANI-Cu₂Modifying the glassy carbon electrode by O nano powder to obtain polyphenylAmine-loaded cuprous oxide sensing electrode.

Description

Polyaniline-loaded cuprous oxide sensing electrode and preparation thereof

Technical Field

The invention particularly relates to a polyaniline-loaded cuprous oxide sensing electrode and a preparation method thereof.

Background

Dopamine (DA) is an important neurotransmitter in the mammalian central nervous system. Low levels of DA can cause neurological dysfunction such as parkinson's disease, schizophrenia, and the like. Therefore, DA is a hot spot of research by neurologists and chemists at present, and development of a rapid and simple method for measuring DA concentration is also an important matter of attention by researchers at present. Uric Acid (UA) is the major end product of purine metabolism. Studies have shown that extremely abnormal UA levels are closely associated with several diseases, such as gout, hyperuricemia, and Lesch-Nyan disease, among others. Since UA and DA are often present in both extracellular fluid and blood of the central nervous system, simultaneous detection of DA and UA is of great significance in routine assays.

At present, the main testing methods of DA and UA include ultraviolet visible spectrophotometry, fluorescence, chemiluminescence, high performance liquid chromatography and other analysis technologies. However, these methods are complicated, costly, time-consuming, and their low sensitivity of detection limits their clinical applications. Due to the electrochemical activity of DA and UA, electrochemical detection methods thereof become hot spots of current research. However, due to the fact that DA and UA molecular structures are approximate, oxidation peaks of DA and UA molecular structures on a conventional bare electrode are overlapped, and the DA and UA molecular structures cannot be tested by the conventional bare electrode.

Disclosure of Invention

The invention provides polyaniline-loaded cuprous oxide (PANI-Cu)₂O) DA and UA selective electrochemical detection electrode and preparation method thereof can effectively solve the problems of simultaneous detection, anti-interference and sensitivity of DA and UA.

In order to solve the technical problems, the invention adopts the technical scheme that:

a preparation method of a polyaniline loaded cuprous oxide sensing electrode comprises the following steps:

s1: adding 0.5mL aniline monomer into 50mL dichloromethane solution, and performing ultrasonic treatment to uniformly disperse the aniline monomer to form transparent and uniform organic phase solution;

s2: adding 50mL of 0.2mol/L N-methyl pyrrolidone aqueous solution and 2.323g of camphorsulfonic acid into the organic phase solution in sequence under the condition of stirring, stirring at room temperature for a preset time, and standing;

s3: slowly adding 5mL of 0.06g/mL ammonium persulfate aqueous solution into the reaction solution prepared by S2, standing for reaction for a preset time, separating lower-layer dichloromethane, and filtering the rest solution through a mixed system filter membrane to obtain a solid product;

s4: cleaning and drying the solid product to obtain camphorsulfonic acid doped PANI nano powder;

s5: ultrasonically dispersing 160mg camphorsulfonic acid doped PANI nano powder in 50ml ethylene glycol solution, then adding 0.25g blue vitriol and 0.04g PVP and stirring, then dropwise adding 25ml 0.09M sodium hydroxide aqueous solution and stirring, stirring for a preset time, adding 25ml 1.3M glucose aqueous solution and continuing stirring for a period of time, then stirring and reacting for 1-2h at 80 ℃, filtering a product after the reaction is finished through a mixed system filter membrane, washing and drying a solid product obtained by filtering, and obtaining PANI-Cu₂O nano powder;

s6: polishing a glassy carbon electrode on a polishing pad by using alumina slurry with the grain diameters of 3 microns, 1 micron, 0.3 micron and 0.05 micron in sequence, then washing with distilled water, ultrasonically cleaning in absolute ethyl alcohol and distilled water respectively, and airing for later use;

s7: 2mg of PANI-Cu₂Adding O nano powder and 10 mul of 5% Nafion ethanol solution into 0.5ml of ethanol and performing ultrasonic dispersion to form uniform mixed suspension;

s8: dripping 20 mu l of the mixed suspension onto the surface of the cleaned glassy carbon electrode, and airing at room temperature to obtain PANI-Cu₂And O modifying the electrode.

As a further improvement, the preparation method of the polyaniline-loaded cuprous oxide sensing electrode further comprises the step of preparing the prepared PANI-Cu₂Performing Cyclic Voltammetry (CV) sweep on the O modified electrode for 2h under the conditions of 0.1M PBS (pH 6.8) and potential range of-0.1V-0.9V (vs. SCE), and then scanning for 30min under the condition of constant potential of 0V; after repeating the above operation 3 times, the treated modified electrode was immersed in a 0.1M PBS solution for use.

The invention also provides a method based onThe test environment of the polyaniline loaded cuprous oxide sensing electrode prepared by the preparation method is as follows: with PANI-Cu₂The O modified electrode is a working electrode, the graphite electrode is a counter electrode, the Saturated Calomel Electrode (SCE) is a reference electrode, pulse volt-ampere (DPV) test is carried out, the potential range of the DPV test is-0.1V-0.9V (vs. SCE), the scanning amplitude is 50mV, and the pulse width is 50 ms. Wherein the DPV test was performed in 0.1M PBS solution at pH 6.8.

As a further improvement, the modified electrode was potentiostatically scanned at 0V for 30s before each DPV test.

The invention has the beneficial effects that: PANI-Cu prepared by the invention₂The O modified electrode can effectively solve the problem that the overlapping of DA and UA oxidation peaks is difficult to detect, and can realize the simultaneous detection of DA and UA; in addition, the detection limit of the modified electrode to DA is 0.001 μ M (expected to be used for detecting the content of DA in the extracellular fluid of the Parkinson patient); the detection limit of the reagent to UA is 1 mu M, and the reagent has higher sensitivity.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 shows PANI and PANI-Cu₂SEM image of O nanocatalyst.

FIG. 2 shows PANI-Cu₂DPV test plots of O nanocatalyst-modified electrodes in 0.1M PBS (pH 6.8) containing 1mM UA, 2mM AA, and 200. mu.M DA.

FIG. 3 shows PANI and PANI-Cu₂Comparative graph for DPV testing of O nanocatalyst modified electrodes in 0.1M PBS (pH 6.8) solution containing 200 μ M DA (a) and 1mM UA (B).

FIG. 4 shows PANI-Cu₂DPV test plots of O-modified electrodes in 0.1M PBS (pH 6.8) solutions containing different concentrations of DA.

FIG. 5 shows DA in PANI-Cu₂O modificationStandard curve for DPV test on electrode.

FIG. 6 shows PANI-Cu₂DPV test plots of O-modified electrodes in 0.1M PBS (pH 6.8) solutions containing different concentrations of UA.

FIG. 7 shows UA in PANI-Cu₂O modifies the standard curve for DPV testing on the electrode.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The embodiment of the invention provides a preparation method of a polyaniline-loaded cuprous oxide sensing electrode, which comprises the following steps:

As a further improvement, the preparation method of the polyaniline-loaded cuprous oxide sensing electrode further comprises the step of preparing the prepared PANI-Cu₂Performing Cyclic Voltammetry (CV) sweep on the O modified electrode for 2h under the conditions of 0.1M PBS (pH 6.8) and potential range of-0.1V-0.9V (vs. SCE), and then scanning for 30min under the condition of constant potential of 0V; and repeating the operation for 3 times, and soaking the treated modified electrode in 0.1M PBS solution for later use, namely, pretreating the prepared catalyst modified electrode to obtain a stable electrochemical detection signal with good repeatability in the electrochemical test process.

As a further improvement, the stirring time at room temperature in S2 is 20-30 min.

As a further improvement, the standing reaction time in S3 is 60-90 min.

As a further improvement, the specific steps of S4 are: washing the solid product with distilled water and ethanol in sequence, and filtering to obtain the final product, and naturally drying to obtain the camphorsulfonic acid doped PANI nano powder.

As a further improvement, copper sulfate pentahydrate and PVP are added into S5 and stirred for 30 min; dropwise adding sodium hydroxide aqueous solution and stirring for 20-30 min; adding glucose water solution, and stirring for 20-30 min.

As a further improvement, the specific steps of washing and drying the solid product in S5 are as follows: washing the solid product with anhydrous ethanol and pure water for 4-6 times, and naturally drying to obtain PANI-Cu₂O nanometer powder.

The test environment of the polyaniline-loaded cuprous oxide sensing electrode prepared based on the preparation method is as follows: with PANI-Cu₂The O modified electrode is a working electrode, the graphite electrode is a counter electrode, the Saturated Calomel Electrode (SCE) is a reference electrode, pulse volt-ampere (DPV) test is carried out, the potential range of the DPV test is-0.1V-0.9V (vs. SCE), the scanning amplitude is 50mV, and the pulse width is 50 ms. Wherein the DPV test was performed in 0.1M PBS solution at pH 6.8. Before each DPV test, scanning the modified electrode at a constant potential for 30s under the condition of 0V to enable the modified electrode material to be in an electrochemical reduction state so as to obtain a stable and high-sensitivity electrochemical signal.

Example 1

50mL of methylene chloride was added to a round bottom flask, and 0.5mL of aniline monomer was added to the methylene chloride solution and uniformly dispersed by sonication to form a clear and homogeneous solution of the organic phase. The obtained organic phase solution was placed on a magnetic stirrer, 50mL of 0.2mol/L N-methylpyrrolidone aqueous solution was added to the solution under stirring, 2.323g of camphorsulfonic acid was added thereto, and the mixture was stirred at room temperature for 20 minutes and then allowed to stand. 0.3g of ammonium persulfate is weighed and dissolved in 5mL of water, after the ammonium persulfate solution is completely dissolved, the ammonium persulfate solution is slowly added into the dichloromethane-N-methyl pyrrolidone reaction solution under the standing condition along the bottle wall of the round-bottom flask, and after the dichloromethane reaction solution is kept standing for 60 minutes, the lower layer of dichloromethane is sucked out by a rubber head dropper and poured into a waste liquid bottle. Filtering the residual solution with a mixed system filter membrane with the aperture of 0.22 mu m to obtain a solid product, washing and cleaning the filtered product with distilled water and ethanol in sequence, and naturally airing to obtain the camphorsulfonic acid doped PANI nano powder.

And (2) taking 160mg of camphorsulfonic acid doped polyaniline powder, performing ultrasonic dispersion in 50ml of glycol solution, adding 0.25g of copper sulfate pentahydrate and 0.04g of PVP, stirring for 30min, then dropwise adding 25ml of 0.09M sodium hydroxide aqueous solution, stirring for 20min, adding 25ml of 1.3M glucose aqueous solution, continuing stirring for 20min, transferring to a water bath, and stirring and reacting for 1h at 80 ℃. Filtering the solid product with 0.22 μm mixed system filter membrane, washing with anhydrous ethanol and pure water for 4-6 times, and naturally air drying to obtain PANI-Cu₂O nanometer powder.

And polishing a glassy carbon electrode with the diameter of 5mm on a polishing pad by using alumina slurry with the grain diameters of 3 microns, 1 micron, 0.3 micron and 0.05 micron in sequence, washing by using distilled water, ultrasonically cleaning in absolute ethyl alcohol and distilled water respectively, and airing for later use. 2mg of PANI-Cu₂O nano powder and 10 mul of 5% Nafion ethanol solution are dispersed in 0.5ml ethanol and subjected to ultrasonic treatment for 30min to form a uniform mixed suspension. And dripping 20 mu l of the mixed suspension onto the surface of the cleaned glassy carbon electrode, and airing at room temperature. In order to obtain a stable and well-repeatable electrochemical detection signal, a prepared catalyst modified electrode needs to be pretreated, namely, Cyclic Voltammetry (CV) is swept for 2 hours in 0.1M PBS (pH 6.8) under the condition of a potential range of-0.1V-0.9V (vs. SCE), and then constant potential scanning is carried out for 30min under the condition of 0V; after repeating the above operation 3 times, the pretreated modified electrode was immersed in 0.1M PBS solution for use.

The electrochemical test adopts a three-electrode system in which PANI-Cu is adopted₂And the O modified electrode is a working electrode, the graphite electrode is a counter electrode, and the Saturated Calomel Electrode (SCE) is a reference electrode, and a pulse volt-ampere (DPV) test is carried out. The potential range for the DPV test was-0.1V-0.9V (vs. SCE), the scan amplitude was 50mV, and the pulse width was 50 ms. In order to obtain a stable and highly sensitive electrochemical signal, before each DPV test, the modified electrode is scanned at a constant potential for 30s under the condition of 0V so that the modified electrode material is in an electrochemical reduction state. The entire test was performed in the presence of phosphate buffered saline (0.1M PBS solution, pH 6.8).

Comparative example

And polishing a glassy carbon electrode with the diameter of 5mm on a polishing pad by using alumina slurry with the grain diameters of 3 microns, 1 micron, 0.3 micron and 0.05 micron in sequence, washing by using distilled water, ultrasonically cleaning in absolute ethyl alcohol and distilled water respectively, and airing for later use. 2mg of PANI nano powder and 10. mu.l of 5% Nafion ethanol solution were dispersed in 0.5ml of ethanol and sonicated for 30min to form a homogeneous mixed suspension. And dripping 20 mu l of the mixed suspension onto the surface of the cleaned glassy carbon electrode, and airing at room temperature. In order to obtain a stable and well-repeatable electrochemical detection signal, a prepared catalyst modified electrode needs to be pretreated, namely, Cyclic Voltammetry (CV) is swept for 2 hours in 0.1M PBS (pH 6.8) under the condition of a potential range of-0.1V-0.9V (vs. SCE), and then constant potential scanning is carried out for 30min under the condition of 0V; after repeating the above operation 3 times, the pretreated modified electrode was immersed in 0.1M PBS solution for use.

The electrochemical test adopts a three-electrode system, wherein a PANI modified electrode is used as a working electrode, a graphite electrode is used as a counter electrode, and a Saturated Calomel Electrode (SCE) is used as a reference electrode, so that a pulse volt-ampere (DPV) test is carried out. The potential range for the DPV test was-0.1V-0.9V (vs. SCE), the scan amplitude was 50mV, and the pulse width was 50 ms. In order to obtain a stable and highly sensitive electrochemical signal, before each DPV test, the modified electrode is scanned at a constant potential for 30s under the condition of 0V so that the modified electrode material is in an electrochemical reduction state. The entire test was performed in the presence of phosphate buffered saline (0.1M PBS solution, pH 6.8).

Test example:

FIG. 1 shows PANI and PANI-Cu₂An SEM image of the O nano-catalyst shows that the PANI nano-carrier is of a short fiber structure and has the diameter of 30-60 nm; cu₂O is a series of round particles with the diameter of 10-20nm and is uniformly distributed on the surface of the PANI nano-fiber. PANI-Cu₂Cu in O nano catalyst powder₂The O loading was 10%.

FIG. 2 shows PANI-Cu₂The DPV test chart of the O nano-catalyst modified electrode in 0.1M PBS (pH 6.8) solution containing 1mM UA, 2mM AA and 200. mu.M DA shows that the oxidation current potential range of the DA is 0.06V-0.4V, and the oxidation peak potential is 0.17V; the oxidation current potential range of UA is 0.24V-0.4V, and the oxidation peak is 0.30V. Therefore, in the detection of the DA and UA coexisting system, the detection of DA is not interfered by the existence of UA; the UA concentration in the serum of a healthy human body is generally 120-460 mu M, and the extremely low concentration of DA is 0.01-1 mu M, so that the method provided by the invention is not interfered by DA when being used for detecting the UA concentration in the serum of the human body.

FIG. 3 shows PANI and PANI-Cu₂DPV test comparison of O-nanocatalyst-modified electrodes in 0.1M PBS (pH 6.8) containing 200. mu.M DA (A) and 1mM UA (B), DA in PANI-Cu, as can be seen in FIG. 3A₂Compared with PANI, the oxidation peak potential on the O nano catalyst modified electrode generates certain negative shift, which is beneficial to the anti-interference detection of DA and UA; DA in PANI-Cu₂Compared with PANI, the catalytic oxidation signal on the O nano-catalyst modified electrode is obviously enhanced. As can be seen from FIG. 3B, UA is in PANI-Cu₂Compared with PANI, the catalytic oxidation signal on the O modified electrode is enhanced to a certain extent, and the oxidation peak potential of the O modified electrode is not obviously shifted. Thus, Cu is compounded₂The sensitivity and anti-interference detection of the PANI nano-catalyst modified electrode of O to DA and UA are obviously improved.

FIG. 4 shows PANI-Cu₂DPV test pattern of O modified electrode in 0.1M PBS (pH 6.8) solution containing different concentrations of DA, and it can be seen from the figure that different concentrations of DA are oxidized on the modified electrodeThe electrochemical current potential ranges are all between 0.06V and 0.4V, and the oxidation peak potentials are all around 0.17V; as the concentration of DA increases, the electrochemical response signal of DA on the modified electrode also increases, and the detection limit is 0.001 mu M. The concentration of DA in the extracellular fluid of healthy individuals is 0.01-1. mu.M, while the concentration of DA in the extracellular fluid of Parkinson patients is lower than 1 nM. Therefore, the DA detection method provided by the invention has low enough detection limit and is hopeful to be used for detecting the DA content in the extracellular fluid of the Parkinson patient and is not interfered by UA.

FIG. 5 shows DA in PANI-Cu₂The standard curve of DPV test on O modified electrode can be seen in the figure, the concentration range detected in the invention is 0.001-200 μ M, and the DA concentration and the peak current show a bilinear relation. The linear curve at high concentration (5 mu M-200 mu M) is y-0.00613 x +1.09548, and the correlation coefficient R thereof²0.99065. At low concentration (0.001-5 μ M), the linear curve is y-0.5018 x +0.5135, and the correlation coefficient R is²＝0.95652。

FIG. 6 shows PANI-Cu₂The DPV test chart of the O modified electrode in 0.1M PBS (pH 6.8) solution containing different concentrations of UA shows that the oxidation current potentials of the UA with different concentrations on the modified electrode are all in the range of 0.24V-0.4V, and the oxidation peak potentials are all around 0.3V; as the concentration of UA increases, the electrochemical response signal of UA on the modified electrode also increases, and the detection limit is 1 mu M. Compared with the detection limit of camphorsulfonic acid doped PANI on UA 50 mu M, PANI-Cu₂The detection limit of the O modified electrode to UA is obviously improved. The UA concentration in the serum of a healthy human body is generally 120-460 mu M, and the method provided by the invention has enough sensitivity and can be used for detecting UA in the serum of the human body without being interfered by DA in the serum.

FIG. 7 shows UA in PANI-Cu₂The standard curve of DPV test on the O modified electrode can be seen from the figure, the UA test method provided by the invention has a wider linear detection concentration range of 1 mu M-1mM, the UA concentration and the peak current have a linear relation, the linear curve is y-0.000607 x +0.21267, and the correlation coefficient is R²＝0.99108。

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of a polyaniline loaded cuprous oxide sensing electrode is characterized by comprising the following steps:

s7: 2mg of PANI-Cu₂Adding O nano powder and 10 mul of 5% Nafion ethanol solution into 0.5ml ethanol and performing ultrasonic separationDispersing to form a uniformly mixed suspension;

s8: dripping 20 mu l of the mixed suspension liquid on the surface of the cleaned glassy carbon electrode, and airing to obtain PANI-Cu₂And O modifying the electrode.

2. The preparation method of the polyaniline-loaded cuprous oxide sensing electrode according to 1, characterized by further comprising the step of preparing the PANI-Cu₂Performing Cyclic Voltammetry (CV) sweep on the O modified electrode for 2h under the conditions of 0.1M PBS (pH 6.8) and potential range of-0.1V-0.9V (vs. SCE), and then scanning for 30min under the condition of constant potential of 0V; after repeating the above operation 3 times, the treated modified electrode was immersed in a 0.1M PBS solution for use.

3. The preparation method of the polyaniline-loaded cuprous oxide sensing electrode according to 2 is characterized in that the stirring time at room temperature in S2 is 20-30 min.

4. The preparation method of the polyaniline-loaded cuprous oxide sensing electrode according to 2 is characterized in that the standing reaction time in S3 is 60-90 min.

5. The preparation method of the polyaniline-loaded cuprous oxide sensing electrode according to 2 is characterized in that the specific steps of S4 are as follows: washing the solid product with distilled water and ethanol in sequence, and filtering to obtain the final product, and naturally drying to obtain the camphorsulfonic acid doped PANI nano powder.

6. The preparation method of the polyaniline-loaded cuprous oxide sensing electrode according to 2 is characterized in that copper sulfate pentahydrate and PVP are added into S5 and stirred for 30 min; dropwise adding sodium hydroxide aqueous solution and stirring for 20-30 min; adding glucose water solution, and stirring for 20-30 min.

7. The preparation method of the polyaniline-loaded cuprous oxide sensing electrode according to 2 is characterized in that the steps of washing and drying the solid product in S5 are as follows: solid bodyWashing the product with anhydrous ethanol and pure water for 4-6 times, and naturally drying to obtain PANI-Cu₂O nanometer powder.

8. A polyaniline-loaded cuprous oxide sensing electrode, wherein said polyaniline-loaded cuprous oxide sensing electrode is made by the method of any of claims 2-7; the test environment is as follows: with PANI-Cu₂The O modified electrode is a working electrode, the graphite electrode is a counter electrode, the Saturated Calomel Electrode (SCE) is a reference electrode, pulse volt-ampere (DPV) test is carried out, the potential range of the DPV test is-0.1V-0.9V (vs. SCE), the scanning amplitude is 50mV, and the pulse width is 50 ms.

9. The polyaniline-supported cuprous oxide sensing electrode of claim 8, wherein DPV test is performed in 0.1M PBS solution at pH 6.8.

10. The polyaniline-loaded cuprous oxide sensing electrode of claim 8 or 9, wherein the modified electrode is potentiostatically scanned at 0V for 30s before each DPV test.